I know someone (casually) whose live-in boyfriend has been cheating on her for several months (as in a 7-month relationship with someone else, not just a one-time thing). I really don't know her well, the boyfriend is a coworker of mine. A lot of people know about his relationship with this other woman, but somehow in all of this time, the girlfriend has not found out.
Because I don't know her, I am obviously not going to get involved, but the whole situation got me thinking- if you were in her situation, would you want to know? Would it make a difference if a whole bunch of other people had known all along and no one had clued you in?