Oh - I read your other post too and now I have a totally different perspective. It IS a sexual issue and he IS attracted to men. In this case, I suggest seeking a counselor's help to mediate the issue. It has to be confronted - whether he is gay or bisexsual. I'm suspecting gay since he only gets aroused when you talk sexually about men. So what he is doing now is he is carrying on an emotional affair with this friend of his. He is living out a fantasy of being in a relationship with a man, but without the sex.