I'm a woman in my 30s. I love parties and talking to people, and thank God, because I attend networking events for work. My boyfriend, on the other hand, is an introvert, hates talking to strangers, and loathes "shindigs." How do we balance my longing to go to parties with his desire to stay home?

--Party Girl

Taking an introvert to a party can be a challenge. On the other hand, if it's a Fourth of July party, you know where to find him: hiding in the bathtub with the dogs.

I actually have personal experience in this area. Like you, I'm an extrovert -- which is to say, a party host's worry isn't that I won't have anyone to talk to; it's that I'll tackle three people and waterboard them with sangria till they tell me their life story. Also like you, I have a boyfriend who's an introvert. For him, attending a party is like being shoved into an open grave teeming with live cockroaches -- though, compassionately, it also includes an open bar.

This isn't to say introverts are dysfunctional. They're not. They're differently functional. Brain imaging research by cognitive scientist Debra L. Johnson and her colleagues found that in introverts, sensory input from experience led to more blood flow in the brain (amounting to more stimulation). The path it took was longer and twistier than in extroverts and had a different destination: frontal areas we use for inward thinking like planning, remembering, and problem-solving. So, introverts live it up, too; they just do it on the inside.

Extroverts' brain scans revealed a more direct path for stimuli -- with blood flowing straight to rear areas of the brain used for sensory processing, like listening and touching. They also have less overall blood flow -- translating (in combination with a different neurochemical response) to a need for more social hoo-ha to feel "fed."

Sometimes, you'll really want your boyfriend there with you at a party -- for support, because you enjoy his company, or maybe just to show him off (kind of like a Louis Vuitton handbag with a penis). But understanding that "shindigs" give his brain a beating, consider whether you could sometimes take a friend. When he accompanies you, maybe set a time limit and be understanding if he and the dog retreat to the den.

Sure, mingling makes you feel better, but pushing an introvert to do it is akin to forcing an extrovert to spend an entire week with only the cat and a fern. Before long, they're on with the cable company. Tech support: "What seems to be the problem?" Extrovert: "I'm lonely! Talk to me! Have you ever been arrested? And do you think I should go gluten-free?"

I grabbed my boyfriend's phone to look something up, and I found a Google search for local massage places that offer "happy endings." He says that he and his friends were just goofing off. Am I an idiot to believe him?

--Disturbed

His "goofing off" is reminiscent of the "but I was just curious!" web searches that juries hear about -- stuff like "Does arsenic have a flavor?" "How much antifreeze does it take to kill a 226.5-pound man?" and "Who's got the lowest prices on shovels and tarps?"

Sure, it's POSSIBLE that your boyfriend is telling the truth -- that he and his buddies were searching out massage parlors RIGHT NEARBY! just for a giggle. To determine how likely it actually is, consider that people don't behave randomly. We're each driven by a varying combo of personality traits -- habitual patterns of thinking, emotion, and behavior that are relatively consistent over time and across situations. For example, an introvert will not suddenly become a party animal (unless we're talking the taxidermied kind that's stuck into the "fall leaves" centerpiece).

Research by evolutionary psychologists David Buss and Todd Shackelford found three personality traits that are strong "predictors of susceptibility to infidelity." One is narcissism -- being self-absorbed, admiration-seeking, empathy-deficient, and prone to scheming userhoood. Being low on "conscientiousness" is another -- reflected in being disorganized, unreliable, and lazy, and lacking self-control. Last, there's "psychoticism," which, despite its Bates Motel-like moniker, reflects a con artist-like exploitativeness, impulsivity, and lack of inhibition -- not necessarily exhibiting those things while going all stabby on some lady enjoying a shower.

Consider whether your boyfriend's "just Googling for kicks!" claim is odd and uncharacteristic or whether it's part of a pattern reflecting one or more of the lovely cocktail of traits above. Patterns of behavior predict future patterns of behavior -- for example, trying to get you to believe that he only goes to strip clubs for the music and that he really was just working late with his boss, Mr. Camerino, who seems to have developed quite a thing for body glitter.

I'm a man in my mid-30s, and I'm dating a woman I really love. We match each other on so many levels, and I thought we had a really great thing. But, recently, she seems to want more than I can give. Specifically, she's prodding me to say "I love you" repeatedly throughout the day, and she blows up at me for not doing it enough. Though I do love her, the required affirmations feel hollow. But I am trying. Yesterday she called, and I told her, "I've been thinking about you all day." She got super angry and said, "Then you should have called to tell me that!" WTH?! Where's the line between being present for someone and being phony just to quell their unfounded insecurity?

--Besieged

Understandably, if your relationship is patterned on a movie, you'd like it to be "Love Actually," not "Judgment at Nuremberg."

Sure, things are looking bleak at the moment. In fact, the best thing about your relationship right now probably seems like the right to a speedy trial. However, you may be able to change that -- get back to the "really great thing" you two had -- by understanding the possible evolutionary roots to your girlfriend's morphing into LOVEMEEEE!zilla.

It turns out that perceiving things accurately isn't always in our best interest. In fact, evolutionary psychologist Martie Haselton explains that we seem to have evolved to make protective errors in judgment -- either underperceiving or overperceiving depending on which error would be the "least costly" to our mating and survival interests.

For example, Haselton explains that men are prone to err on the side of overestimating women's interest in them. Evolutionarily, it's costlier for a man to miss an opportunity to pass on his genes than, say, to get jeered by his buddies after he hits on some model. Man: "Yerrr pritty!" Model: "Um, you're missing most of your teeth."

Women, however, err on the side of underestimating a man's willingness to stick around. This helps keep them from getting duped by cads posing as wannabe dads. And, as Haselton points out, a woman's expressions of "commitment skepticism" may come with a fringe benefit -- "more frequent displays of commitment" (like flowers, prezzies, mooshywooshy talk) from a man "who truly (is) committed."

Unfortunately, your girlfriend's expressing her "commitment skepticism" in exactly the wrong way -- by trying to berate you into being more loving. Practically speaking, this is like running alongside somebody and asking them to explain the tax code while they're being chased by a mob with flaming pitchforks.

Because our brain's "fight or flight" circuitry is also calibrated to protectively overreact, a verbal attack kicks off the same physiological responses as a physical one. Adrenaline surges. Your heart beats faster. And blood flow gets shunted away from systems not needed to fight back or bolt -- like digestion and higher reasoning. This makes sense, because you don't need algebra to keep a tiger from getting close enough for you to notice his need for Crest Whitestrips. Only -- oops -- higher reasoning is exactly what you need when it's only your girlfriend chasing after you for a little more loveydoveyspeak.

Of course, you understand that your girlfriend is a lady looking for your love, not a tiger looking to turn you into a late lunch. However, once that fight-or-flight train leaves the station, it keeps building momentum. (You can't just treat your surging adrenaline like a bratty third-grader and tell it to go sit down.)

So, though the problem between you might seem to start with your girlfriend, consider what psychologist Brooke C. Feeney calls "the dependency paradox." Feeney's research suggests that continually responding to your romantic partner's bids for comforting (like expressions of neediness) with actual comforting seems to alleviate their need for so much of it.

This isn't to say you should make like a meth-jacked parrot and start squawking "Awwk! I love you!" until -- thunk! -- you beak-plant on the newspapers lining your cage. Instead, start by asking your girlfriend why she feels a need for this daily stream of "affirmations." (Some women get wiggy when, weekend brunch after weekend brunch, there's never a diamond ring under their waffles.)

Next, explain the science, including Feeney's finding. Then, pledge to be more expressive in general (holding her, telling her you love her), but explain that you feel insincere punctuating every text and conversation with robo I-love-yous. As for her part, point out that if, instead of going off on you, she'd express her fears, it would put you in a position to reassure her. Ultimately, if you're yelling "I love you!...I love you!" it should be because she's running to catch a plane, not because you just can't take another weekend chained to the radiator.

I love my boyfriend; however, I feel bad that he never buys me presents. He did when we were dating, and he buys himself extravagant stuff. But he got me nothing for my birthday and only some trinkets for Christmas because I made a stink. When I've brought up the gifts issue, he's implied that I'm materialistic. However, what matters to me is not the cost but that he's thinking of me. Is my desire for gifts somehow shallow?

--Coal Digger

Once again, it's Christmas. Ooh, ooh, what's that under the tree?! Once again...it's the floor.

Many men sneer at the importance their ladies place on getting gifts from them, deeming it a sign of female emotional frailty. What these men aren't taking into account is that the differences that evolved in male and female psychology correspond to differences in male and female physiology. To put this another way, women -- disproportionately -- are into getting gifts from romantic partners for the same reason men (disproportionately) are into watching strippers. ("All the better to pass one's genes on with, my dear!")

Because, for a woman, sex can lead to pregnancy (and a hungry kid to drag around), female emotions evolved to act as a sort of alarm system, making a woman feel crappy when there are signs a man's commitment may be waning. (Wanting to feel better makes her take corrective action -- pressing him to put up or get out.) However, a man's being willing to give gifts suggests a willingness to "invest" (beyond 2.6 minutes of foreplay and a teaspoon of sperm).

Accordingly, evolutionary behavioral scientist Gad Saad believes that gift-giving evolved as a "distinctly male courtship strategy." Though women do give gifts to romantic partners, they tend to wait till they're in a relationship and then do it to "celebrate" being together. Saad's research finds that men, on the other hand, "are much more likely to be tactical in their reasons for offering a gift to a romantic partner" -- like, in the courtship phase, to get a woman into bed. (Of course, if a woman wants to get a man into bed, she doesn't need to give him a present to unwrap; she just starts unbuttoning her top.)

Explain the science to your boyfriend. You don't have a character deficiency; you just want him to show his love in the way that works for you. That's what people who love each other do -- even if they, say, believe the gift of their side salad at dinner should be gift enough. Besides, you aren't demanding, "'Tiara of the Week!' or I'm gone!" You'd just like occasional little "thinking of you" prezzies and somewhat bigger ones on Official Girlfriend Holidays (birthdays, anniversaries, etc.). Ultimately, these are not just gifts but messages that making you happy is worth an investment of money and effort -- beyond what he's been putting in to run out and get his wallet wired shut just in time for your birthday.

My fiancee and I were driving my drunk friend home from a party. He was saying rude things to her, but I knew he was just wasted and didn't mean them, so I didn't say anything. I thought my fiancee would also shrug it off, but she was mad and hurt that I didn't stand up for her. Is it that big a deal? Couldn't she have stood up for herself?

--Middleman

Yes, there's actually more to being an ideal partner to a woman than being able to unhook a bra with your teeth.

A woman today may be perfectly capable of defending herself -- with her big mouth or her big pink handgun. However, she has an emotional operating system pushing her to go for men who show an ability and a willingness to protect her. This comes out of how, over millions of years of evolution, certain ladies' children were more likely to survive and pass on their mother's genes (and the psychology that rides along). Which children? Those whose mothers chose men who'd do more in an attack than, well, effectively crawl under the car seat and wish all the awfulness would stop.

Your fiancee probably still feels resentful and maybe even thinks less of you for how you basically showed all the testosterone-driven fortitude of a geranium. Consider what grandpas everywhere call "having character": doing the right thing -- even when that kinda blows for you. If, in looking back, you would've done things differently, tell your fiancee. Then pledge that going forward, you'll be that kind of guy -- and protecting the person who means most to you won't involve pushing your girlfriend toward the grizzly bear so you'll have more time to make a run for it.

I'm extremely insecure about my looks, though objectively, I know I'm pretty. I constantly ask my boyfriend for reassurance. He gives it to me but feels bad that I feel this way. Now I'm worrying that I'm making such a good case for what's wrong with me that he'll start believing me. Possible?

--Bag Over Head

One oft-overlooked beauty secret is to avoid constantly giving a guy the idea that you might actually be ugly.

People will sneer that it's "shallow" to care about how you look, and they're probably right -- if it's all you care about. However, research confirms what most of us recognize about the especially eye-pleasing among us: They get all sorts of benefits -- everything from social perks to job opportunities to discounts when they act like dirtbags (with judges assigning them lesser fines and a lower rate of bail for misdemeanors).

As a woman, being babe-alicious is a pretty vital tool for landing and maintaining a relationship, because the features that men -- across cultures -- evolved to consider beautiful are actually health and fertility indicators. So, for example, full lips and an hourglass bod are basically evolution's bumper sticker: "Your genes passed on here!"

Not surprisingly, psychologist Tracy Vaillaincourt, who researches competition among women, explains that women attack other women "principally on appearance and sexual fidelity" because men prioritize these qualities in their partners. One way women chip away at the competition is by trash-talking another woman's looks to a man -- suggesting he really could do better. That's what you're doing -- but to yourself. It's the relationship version of "Ewww, you're not really gonna eat that, are you?" (And you're the fricasseed crickets.)

Beyond that, constantly begging a romantic partner for reassurance -- while being kind of a black hole for it -- can be toxic to a relationship. Also, the fact that your need for reassurance seems bottomless suggests it's not your exterior but your interior that's in need of work. Get cracking on that, and try to remember that your boyfriend is with you for a reason -- and it probably isn't that your mom and grandma are crouched behind your sofa, holding him at gunpoint.

I'm a woman in my 30s. I was married for five years, but now, thank God, I'm divorced and about two years into a wonderful new relationship. Disturbingly, I occasionally call my boyfriend by my awful ex-husband's name. He laughs it off, but it really freaks me out. Should I see a neurologist? Is my memory going? Or -- gulp -- do I miss my ex on some subconscious level?

--Disturbed

Right about now, you've got to be recognizing the unexpected benefits of those gas station attendant shirts with the guy's name sewn onto them.

As with dead bodies carelessly submerged after mob hits, it's unsettling to have your ex's name bobbing up when you love somebody new. Naturally, you suspect the worst -- that you're subconsciously pining for the ex. But -- good news! -- the likely reason for your name swapperoos is something you should find comfortingly boring. According to research by cognitive scientists Samantha Deffler and David C. Rubin, we're prone to grab the wrong name out of memory when both names are in the same category -- for example, men you've been seriously involved with or, in the pet domain, gerbils you've dressed in tiny sexy outfits.

You might also keep in mind that your ex's name was the default for "man in my life" for more than twice as long as the new guy's. Other memory research suggests that especially when you're tired, stressed, or multitasky, it's easy to go a little, uh, cognitively imprecise. You send your mindslave off into your brain -- back to the "My Guy" category -- and the lazy little peasant just grabs the name he spent five years grabbing. So, you might think of this as a mental workforce issue. The Department of Emotions isn't even involved.

However, research by cognitive psychologist Robert Bjork suggests that you can train your memory to do better through "spaced retrieval" -- correcting yourself just post-flub by asking and answering "Who is the man in my life?" and then letting a few minutes pass and doing it again. But considering that you have a partner who just laughs at your errors, your time would probably be better spent appreciating what you have: an easygoing sweetheart of a guy and no readily apparent need for a neurologist. Bottom line: Your calling the guy by the wrong name probably points to a need for a nap, not unwanted company -- as in, a tumor named Fred squatting in the crawlspace behind your frontal lobe.

Nobody expects a free meal from a restaurant. So what's with wedding guests who think it's acceptable to give no gift or just $100 from two people? My understanding is that you are supposed to "cover your plate" -- the cost of your meal (at least $100 per person). If you can't, you shouldn't attend. I'm planning my wedding and considering not inviting four couples who gave no gift at my two siblings' weddings. Upsettingly, most are family members (and aren't poor). I'd hate to cut out family, but if they won't contribute, what else can I do?

--Angry Bride

If gift price is tied to meal price, it seems there should be a sliding scale. Uncle Bob, who'll singlehandedly suck down 16 trays of canapes and drain the open bar, should pony up for that Hermès toaster oven. But then there's Leslie, that raw vegan who only drinks by licking dew off leaves. Whaddya think...can she get by with a garlic press and a handmade hemp card?

The truth is, this "cover your plate" thing is not a rule. It's just an ugly idea that's gained traction in parts of the country -- those where bridezillas have transformed getting married into a fierce social deathmatch, the wedding spendathalon. What gets lost in this struggle to out-lavish the competition is the point of the wedding -- publicly joining two people in marriage, not separating their friends and relatives from as much cash as possible. And though it's customary for guests to give gifts, The Oxford English Dictionary defines "gift" as "a thing given willingly" -- as opposed to "a mandatory cover charge to help fund the rented chocolate waterfall, complete with white mocha rapids and four-story slide manned by Mick Jagger and Jon Bon Jovi."

But because you -- incorrectly -- believe that guests owe you (more than their company), you've awakened your ancient inner accountant, the human cheater-detection system. Evolutionary psychologists Leda Cosmides and John Tooby describe this as a specialized module the human brain evolved for detecting cheaters -- "people who have intentionally taken the benefit specified in a social exchange rule without satisfying the requirement."

Identifying and punishing freeloading slackers was especially vital in an ancestral environment, where there weren't always enough grubs to go around. These days, however, maybe you have the luxury to do as I advise in "Good Manners for Nice People Who Sometimes Say F*ck": refuse to let a few (apparent) Stingy McMingies shape "who you are -- which is created through ... how you behave." Instead of grinding down into tit for tat, you can decide to be generous. It's a thematically nice way to start a marriage -- in which 50/50 can sometimes be 95/"Hey, don't I at least get your 5 percent?" It also makes for a far less cluttered invitation than "RSVP...with the price of the gift you're getting us -- so we know whether to serve you the Cornish game hen at the table or the bowl of water on the floor. Thanks!"

Though my boyfriend is loving and attentive, he's bad at responding to my texts. He's especially bad while traveling, which he does often for his work. Granted, half my texts are silly memes. I know these things aren't important, so why do I feel so hurt when he doesn't reply?

--Waiting

You'd just like your boyfriend to be more responsive than a gigantic hole. (Yell into the Grand Canyon and you'll get a reply. And it isn't even having sex with you.)

What's getting lost here is the purpose of the GIF of parakeets re-enacting the Ali/Frazier fight or the cat flying through space on the burrito. Consider that, in the chase phase, some men text like crazy, hoping to banter a woman into bed. But once there's a relationship, men (disproportionately) use texting as a logistical tool -- "b there in 5" -- while women continue using it as a tool for emotional connection. That's probably why you feel so bad. Feeling ignored is also not ideal for a relationship. In research psychologist John Gottman did on newly married couples, the newlyweds who were still together six years down the line were those who were responsive toward their partner's "bids for connection" -- consistently meeting them with love, encouragement, support, or just attention.

Explain this "bids for connection" thing to your boyfriend. (That mongoose in a dress is just meme-ese for "Yoo-hoo! You still there?") However, especially when he's traveling, a little reasonableness from you in what counts as a reply should go a long way. Maybe tell him you'd be happy with "Ha!", "LOL," or an emoji. You'd just like to see more than your own blinking cursor -- looking like Morse code for "If he loved you, he'd at least text you that smiling swirl of poo."