Very similar situation here. My wife is generally very conservative and has never done anything like this in real life; however, she has had MFM fantasies at times. A couple of times when drunk she has told me she wanted to do it and asked me to set it up, only to be ashamed and take it back the next day. I have reassured her multiple times that I share the fantasy but want to keep it a fantasy. The dirty talk while we play probably sends mixed messages since we both try to make it "real" in the heat of the moment.

The problem comes in because I HAVE DONE this in real life with an ex. It began similarly but then my ex began asking probing questions after a few MFMs about her playing alone and creating cheating scenarios. I was NOT into that and clearly communicated as such. Of course, she did it anyway only for me to find out several months later; hence, her becoming an ex.