If there are 37 adults in a tribe, unless otherwise stipulated (and it wasn't), that means approximately half are men and half are women. How the fuck are 18 women having 88 affairs with just one or two men? That doesn't even make any sense. You're just being absurd.

The Mosuo are a matrilineal culture where everyone lives in the home of their mother or grandmother and there is no social concept of husbands or fathers. So no, in that culture one or two men are not having harems of women either. In fact, other than Genghis Khan, and a very few other sultans and kings with harems, there has never been any widespread dynamic where only a few men had sex with a lot of women and the rest of the men had nobody. Besides being a stupid incel narrative, it wouldn't exactly be evolutionarily very sound. Why don't you do something constructive and analyze the math of just how non-adaptive such a construct would be so you can stop worrying about it.