Every MC in just about every VN can be considered a whore. They ALL sleep with multiple women, and almost ALWAYS keep it to themselves until it blows up in their faces. Very rarely do you find MCs that actually tell the women they're in relationships with, that they sleep with pretty much anyone that looks at them.
Some people play these games to live out their fantasies or some shit while others simply enjoy the stories. (Not gonna lie, the stories have been more enjoyable than half of the AAA trash I've played in the past 5 years.)
The only expectation that 99% of the people who play these games has is that none of the Love Interests in these games EVER have sex with another man. ESPECIALLY when the MC is ACTIVELY pursuing said Love Interest or already IN A RELATIONSHIP with said Love Interest (irrelevant for New Horizons, but IS relevant for My Best Deal)
The Love Interests can only have sex with other men if it is COMPLETELY OPTIONAL and (very rarely) A PUNISHMENT FOR BAD CHOICES (Caribdis found out that using it as a punishment [Once in a Lifetime] is still decently frowned upon, hence the very rarely)
Even then, sometimes the hatred CAN be a bit extreme. For instance ECHOES (by Oldcat/Lyk4n) has a scene in the past where the MC catches his ex cheating on him. The MC then uses this experience that he utterly despised to grow and develop as a person by trying to be less shy/antisocial and be more like the jocks in some ways. Anyways, People apparently gave the dev so much hate for it that he has basically gone on vacation until January despite it being... ok... (MC didn't actively cheer it on/encourage it, MC fell to his knees and knocked open the door, MC didn't watch the full scene, and the MC was utterly heartbroken and felt betrayed.)
So, those are my observations from roughly 3 (three) years of dwelling in these types of communities. (1 year of lurking without an account and 2 years of actually having an account)