I think the problem with the A/B/C options is, that most storys have somehow transitions from her liking of the whole cheating.
So most time I see NTR in games/mangas it's the B type. Simple reason: The girl likes it, so the stealing is "right" and the humilation is worse for the partner, because she is loving it. And Bonus: in the beginning it looks like the original couple would be perfect. With all these together: mostly this is the version in which you play the girl.
Bringing the next thing to NTR which is somehow important if you play as male...mystery. You get informed she is doing something with her best friend (MC ist most naive, so here is the first lie) and so it goes on, till the "climax" where all is revealed (so you don't know anything about her cheating). Pro: Extra strong feelings incoming, Contra: in a game you will not see anything sexual for a long time...
And with that comes the special option: avoiding. Everyone want to see the happy ending (okay some not all) and so: make it avoidable or you just feel like your decisions doesn't matter.
One last option is the sandbox-gameplay, which is some complex point: sandbox meaning no ending is bad for NTR (because when you chase a girl and she jumps between you and the NTR-guy it's not really satisfying (look for the tyrant: you have <5 friendship she is cheating. going above : bam she is super loyal).
But having a way to go for the "best" ending (means: question a take answer c, questin B take answer B, on day four do xyz, then zyx) is nice for searching the best route, but also elimnates the idea of "free decisions". And THIS is one of the hardest parts for the dev, and maybe the writer.
So what would a real good NTR-game deliver:
male protag (because most players are male) -> stronger "feelings"
more than one love-interest -> go for more than one girl (also if not setting them up for harem) is always a nice to have
mystery -> you doesn't really know IF there is anything ongoing till it's too late
avoidable -> because you are playing a game, not a kinetic-novel...
sandbox -> because we want to try many ways of winning/loosing
And to bring all these together in one game, and giving us also some "sandbox" options...the holy grail: people believe in it, but nobody has found it till today...
Okay long text, that above is all something I personal want to see in a good game, so anyone else may want to see something else. End.
Merry Christmas to you all.