I have yet to see a single game (that did not involve the MC courting and finally shtupping his virgin girlfriend without either of them first fucking around...so not a single game yet), that wasn't about or didn't include sharing in some way shape or form....
Because more often than not, the MC is a man-whore who is passed around faster and more often than a AV game on this forum...... Which necessarily means that he's shared by the (wo)men he interacts with, often knowingly so.
Usually these discussions devolve into posturing, dick-waving, ad hominem attacks, grandiose declarations of "facts and truths" that are usually either an opinion or at most a matter of perspective, often not a very broad or coherent one, presented for the sake of winning the debate.
The better option would probably be to recognise that it's almost always a matter of personal preference that we then try to wrap around logic arguments...
Which is unnecessary and flawed from the get go, when at the root of the argument presented is indeed an individual opinion or preference.
The fact that these discussions only seem to flare up when that sharing is in one specific direction seems intellectually dishonest to me.
Nobody complains or debates these things when the MC is having a threesome, cheating or making other women cheat. Or worse, proving he's a sociopath with multiple personality disorder by declaring unending love to a bunch of women whilst sneaking around and failing to mention the other women or the idea of polyamory to anyone (which would be fine if the character at least acknowledged being a player and a lying cheat.. But no, as players we're supposed to suspend disbelief and take him seriously)
Everybody seems to care about defining sharing, ntr, cuck, and then appropriateness of it all only if it happens to them/their character...
Which to me is pretty funny