JOHN is a very bad example here. I have tried that game but it sucks in amount of sex scenes as for AVN. And I mean it REALLY lacks them. I don't try to defend The Office, I played it 2 years ago, and then the corruption of the office worker was quite enjoyable
Well JOHN isn't even that deep into the story yet (because updates are quite small and we only get like maybe one or two of those a year, at best), so that considered that's surprisingly many sex scenes, most of which are with her own boyfriend, or at least half of them are.
EDIT: But regardless of how many sex scenes there are in the game, they all occur based on player choices and if one opts to only have her have sex with her boyfriend, then that's entirely possible, she won't be a cheater for any reason, or if someone wants to make her a cheater, that's possible too. And that's was the point, not the amount of sex a game has xD