First, don't tell her that you dont like him, and the things he does. TELL HIM. Nothing like a man standing up and being a man for his woman. Kinda scary to go through her. Just sit him down, face to face (not over the phone) and tell him how you feel like he is crossing the line. Oh, and don't be all friendly about it, let him know you aint playing around or think its funny. Thats how i'd handle it. I look at cheating like this, if you dont have a trust, you dont have a relationship. Also, if its gonna happen, itll happen and you can't really stop it, if that person wants it bad enough, they are going to do it regardless. Its pretty much a waste of time spending your whole relationship snooping around or worrying all the time if this person is going to cheat on you or what not.   Just my 2 Cents sir.