I think you missed the point I was trying to make, in that instance the NTR would be a punishment, your girlfriend after catching you cheating would get revenge by fucking your rival or best friend, then sending you photos/movies to rub it in.
I get what you are saying, it definately sucks when you are NTR'd after making the "correct" choice, but you don't need to be to clever to predict if you take your girlfriend to a party full of horny frat boys only to then ditch her there to go fuck some random slut, then there will a reasonable chance she might end up being fucked by someone who isn't you, particularly if that someone told her what you ditched her to do.
The Bait and switch thing is meant specifically for the whinners, so many Devs abandon games because all the trolling destroys their will to continue, it amuses me to imagine the looks on their faces at that conclusion, like I said in my previous post, that wouldn't be my first choice in how to end a game (if you played it honestly anyway, I might make it something that happens to stat cheaters), it would purely be an act of revenge. I'd more likely have it as one of the possible endings that might happen if the MC has been either too inattentive to the needs of his love interests or has been failing to keep his rivals in check.