@TrapCard113 I have to keep posting this, but the MC is not a virgin and he's already plowed the entire current harem except for the Demon and Dragon chicks.
@xyzzy They're horny bitches that don't want to be left out of the orgy. Plus one on one sex in harem series tend to develop emotional ties to that specific woman, leading the MC to chose her more over the others. Just look at RL Kings and their wife/concubines, the one that the King cares for more at the time is the one that is called for more and gets favored more.