lol almost instantly forgot i made this thread and now it's blown up a lil bit.
Thanks for all the info everyone. And there's been some interesting discussion too.
Personally for me this kink isn't about emasculating or dominating some other dude by stealing his woman or anything like that, which is why cuckolding/Nice Time for Roo stuff is sometimes just a less than ideal substitute (but maybe still close enough to be fun). It's more about the cheating girl (or dude or T or whatevs) doing something they shouldn't and being very naughty. The thrill of being bad and slutty. It's almost in the same vein as something like exhibitionism in that sense.
So it does require monogamy on the part of the couple, and i can see how that would be a bit rare in a game like this.
Anyway, that was what i was looking for/hoping to see in the game!