This may come across very insensitive, but no where in your thread have I noticed that you refered to yourself as a man. I looked carefully at the wording and realized that it could have been written by a woman.......especially when you said she went out with you and the girls. So, I'll just ask, are you a woman and that is why you told her that the two of you knew it would not work with her cheating with a Man?
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!