We should think carefully about the tools various cultures use to deal with sex. Ultimately, sex is about children, humans are a species that reproduces sexually. Even if there's no chance of pregnancy, the chemicals and emotions involved are premised on the possibility of pregnancy.
> The first seems to be present in more liberal, hippie-esque communities I’ve been in. In some circles, all the men seem to be satisfied, and all the women seem to have a lot of sex with a lot of people. I’m extremely curious about what are the causal factors of these types of groups. They seem to have solved the problem.
One of the basic functions of a culture or civilization is to reproduce itself through multiple generations. These communities do not last over long periods of time.