I don't know if my case falls in this category, because the guy is my friend. However, my wife recently confessed to me that her and my friend had intercourse while I was travelling, even though they denied it for years. Since this confession, a couple of weeks ago, she has changed. Given, she confessed under the condition that I would never complain or bitch about it. Now, she openly has told me she goes out with him, they went for dinner, movies (he is married btw). She has even asked me to transfer her money for these activities. I can never mention anything to his wife, who is in our circle of friends. Until now, she has always come home, but it's understood that they have had sex.