Open and honest communication, which equals mutual respect. I actually loved how MC just walked out the door when he caught her cheating, not giving her the satisfaction getting the reaction out of him she so wanted and craved, he made the right choice, not only because she wasn't worth it anymore, but because in anger and when hurt you can say and do things you don't mean. It's just too bad MC never went back sooner to get that closure he so needed, and still apparently needs. (That makes me wonder, why the hell is he still thinking about her? He just had sex with Melissa and told her he loves her and then in his head he sees Ana, the fuck? Haha, guess he still ain't over her.)