Uh, I never had any problems having my wife and (now former) girlfriend in the same room at the same time. The thought that there might be some problem never crossed my mind. Heck, we went camping together and slept in the same tent--my gf and I woke up my wife early the next morning making noise while fucking. My wife looked to see what was making the noise, saw it was us, rolled over and went back to sleep.
I don't think I can help you with this. My experience doesn't include any sort of discomfort with having wife and gf around at the same time. I would think it odd that one of them had any problem with me showing affection to the other.