I'm seeing this new guy, but his ex-girlfriend is absolutely awful: rude, unfriendly, and less-than-intelligent. It makes me question his judgment. If he's interested in a girl like that, I'm not sure I want to be with him.

--Legitimate Fear?

Really good sex can keep a man from seeing the romantic hellshow he's in, especially when the thinking cap he automatically reaches for comes from a small square package marked "Trojan."

We assume someone's romantic partners are a result of carefully reasoned choices. In fact, many people meet someone, have sex with them, want more sex, and end up in a relationship -- totally bypassing any assessment of whether this might be a ruinous idea. Eventually, the initial hot-sex fog recedes a little, and their partner's terrible qualities become increasingly apparent. Time to break up, right? Well, there's a problem.

Psychologist Daniel Kahneman explains that we tend to be "loss aversive": deeply disturbed by potential losses (more than we're excited by possible gains). We often succumb to the "sunk cost fallacy": irrationally deciding to continue investing time, money, and/or energy in what we know is a losing gambit, based on the investment we've already made (that is, "sunk" into it in the past). However, that prior investment is gone. The rational approach is seeing whether future investment would pay off sufficiently and, if not, cutting our losses (perhaps while waving a forlorn goodbye to all the days, months, or -- gulp! -- years we wasted).

To determine how active a role your man's judgment played in his previous entanglement, ask him about what he values, in general and in a partner, and then ask what draws him to you. You should see whether he's with you for reasons you respect or whether you're just a random variation on the nasty, kitten-eating sexbots of what might be called "Cinder" (Tinder when a guy's penis repeatedly picks emotional arsonists who'll burn his mental wellness to the ground).

For pages and pages of "science-help" from me, buy my latest book, "Unf*ckology: A Field Guide to Living with Guts and Confidence." It lays out the PROCESS of transforming to live w/confidence.