Wife keeps rehashing the past and won't let it go

Dear Lori and Jeff,

My wife of two years and I seem to have very different ways of dealing with conflicts in our marriage. I am able to get over things pretty quickly and move on but my wife seems to hold on and can’t let go. Even when she seems to have moved on, she inevitably brings things back up as ammunition for an argument or conflict we’re having in the present. I’ve told her many times that this kind of behavior doesn't work for me and she promises to work on it but she never does. Any ideas?

Signed, I Wish She’d Get Over It