@Kamelpov Yeah, my problem with calling him a whore or a courtesan is that he's not benefitting from the relationships nearly as much as the girls. Sure, he might get some info and maybe some connections, but they didn't really require the deep relationships and most certainly not protective amulets and such. Even if you reversed the genders, it wouldn't really chance much. All the adjectives I used would still apply to a woman.
@Soulwarfare In great many harem series the harem members at least know there are other girls/guys and may even know the others well and interact with them. Basically they would often compete with each other for the MC's attention. Traditionally none of them would be the official girlfriend/boyfriend, although they might occasionally call themselves such. In this series it seems like the three girls (so far) might sometimes suspect the MC could have met some other girl, but they all believe they are the MCs main interest, and they don't know the other ones at all. It's quite different from what we call a harem series these days.