Stress Mismanagement
Maybe remembering a horrible event isn't such a good thing. According to an article by David Glenn:

At least two controlled studies suggest that debriefing may delay some people's recovery from trauma --Ýperhaps because it promotes the habit of ruminating over painful images and memories before a wounded psyche is ready to do so. In 2001, Britain's National Health Service listed stress debriefing as "contraindicated."

Maybe the ability to forget is a sort of mental anaesthetic. A friend's husband had his life spared on 9/11 because she had a early-morning meeting. He took their kids to to school -- making him just late enough to his job at the World Trade Center. Almost all of his coworkers were killed. Afterward, his company sent him to a shrink for stress debriefing, which, according to his wife, was very painful for him -- and probably impeded his emotional recovery. What was it supposed to tell him that he didn't already know? That his colleagues died horrible and senseless deaths? That life was random and unfair? Maybe the healthy thing is being allowed to forget -- which is difficult enough after witnessing or experiencing something horrible.

(Glenn piece via Arts & Letters Daily)