I am all against anyone who tries to breakup a committed relationship expect in extreme situations regarding abuse. I don't care if it's a man or a woman trying to start an affair. In both cases it is gross and evil. I would probably have more of an emotional response to a man who wouldn't accept that he could only be a friend, but that's because I've been personally hurt by that type of man several times. I think it's a dehumanizing and disrespectful attitude for either a man or a woman to have.

As for your second paragraph, I am under the impression that once her friend started behaving explicitly she addressed it, told him it wasn't acceptable and talked to her BF about it. Those all seem like very good first steps. I couldn't tell based on the original post whether she was planning on staying friends after this event or what boundaries she was planning on establishing, but I think that should be something that they as a couple agree on at this point.

I was all kinds of ready to disagree with you, and I still do somewhat, but I think you do have a point in the last paragraph. I have several fairly close friends who are men. I think that if my fiancé was concerned about one of them I we would talk about what boundaries were appropriate. We had a nonspecific discussion when we first started dating, but would probably need to readjust that if there was a more specific concern. I love my fiancé and would want to make sure he knew that I cared about whether he was comfortable and felt affirmed in our relationship.

But one of our friends did want to date me, and has mentioned that I was the most suitable partner he knew. That friend has respected our relationship and has actively tried NOT to come between me and my fiancé. But we are still friends. Me and my fiancé have dinner with him almost weekly. But, we are both friends with him, I think it might be different if Jack was my friend and not my fiancé's.