It sucks when past troubles affect present emotions.
I've been there, but I never worry about guys cheating on me anymore. The only person who's miserable in that case is myself and a guy who is going to cheat is going to cheat no matter how much I do or do not worry about it. No point in stressing over something that hasn't happened.
But I'm always the girl who's a little happy when her boyfriend goes out of town, especially one I'm serious with. I'm weird about my space. I need a decent amount of alone time to be happy no matter how in to somebody I am.