I mean, a situation in which you can fuck every girl with no consequences whatsoever and everybody is happy to share you sounds usually like bullshit to me, at least most of the time. I could understand it for a submissive character as the sister, but Sara would probably outright kill you. So if you act like a douche, I would expect at least some characters to react to that, maybe cheating on you, breaking up with you, killing, plotting revenge and stuff. After all, in real life, choices have consequences, right?
So as long as it is something that depends on MC choices, fine by me. I would dislike it if NTR is just forced for the sake of making an audience happy. After all you are a nice, attractive and interesting guy and you clearly care about your women. Forcing that they cheat out of the blue sounds totally against character as I explained above. So yes, if it is forced like that I would dislike it, the same way I would dislike a total fuckfest for the MC for the same reason.