Boyfriend issue

He has cheated in the past on other woman. I think he has been cheated on so much and retaliated that he really has issues. Now he is talking about how he would like to screw one of my friends. He goes through phases where he talks about screwing other woman (my friends) but I have never found him to act on it. I sometimes think it is just talk and other times not so sure. We have been together over 3 years. I don't want to think about him with another woman it would ruin our relationship. Ugh