In-universe, I'm not entirely sure how Deltan society manages to function, though. One description I read of them -- from the novelization perhaps -- says that to Deltans, sex was part of literally every interaction between people and as common as a handshake. Ok, how many people do you casually interact with in a day? How many people do you shake hands with? Imagine if literally every single one of those encounters involved you having sex with them. How would anything ever get done?
Look up bonobos (pygmy chimpanzees) on Wikipedia. They're pretty much proof of concept for this.