Dude mine did that to me to and believe me it killed for the first month or so. Then I talked to a few friends who said that she was mostly doing that to feel wanted again and it was to get her mind off me. The shame is she is just prolonging her own healing by being with some random. Any idiot can go out and get laid but a true feeling, cool, intelligent person realizes that this is not the way to heal and takes the pain to be a better person and learn. Plus whomever the guy is - well he is just a Rebound - I certainly wouldn't want to be him anyway. You sound cool - you'll punch through this. Find a better person than her and treat her good.