Btw, are there some nice games where you cheat on your girlfriend? And its made kind of a plot point, I know that in blanket terms, a LOT of games on this site could fall there. The MC and the cheating girl should be talking about it - how its wrong, how its hot, sneaking around the GF, sneaking teases here and there etc.
There is a path in Lydia colier game that really fits this. Then with being a dik, Bianca on Jill path really seems will fit there too (sadly will have to wait for an update with that one). Then you get some reverse ntr centered games like Confession game.
Anything else? Its fine even if its a side path - just should be somewhat developed, so I dont spend 10 hours playing a game for a 1 minute hidden scene.