> Is the novelty of new partners really that important?
Yes. It is biologically programmed into us and can be seen with such colloquialism as "Variety is the spice of life"
Yes. It is biologically programmed into us and can be seen with such colloquialism as "Variety is the spice of life"
Additionally, being above or below someone's "league" is a bit of an oversimplification, because there are multiple axes to attraction. It's quite possible to be physically yet not mentally attracted to someone, and thus authentically enjoy sexual encounters with people who you'd prefer not to date seriously, let alone marrying.
If you accept both of these situations, it's not difficult to imagine a world in which many women are having sex with men where there's mutual sexual attraction but no possibility for a relationship, because the man is only interested in sex. Of course this happens the other way too, although I'd guess much less often.
An ex of mine (who I'd remained friendly with) once showed me her Tinder messages and it was full of attractive, confident, successful men who clearly were only interested in sex with her, and who didn't mind being almost offensively direct, presumably because they all had lots of other options for sex.