Some things don’t change just because we want them too, we can’t educate out some things.

Brilliant idea, we should stop teaching murder is bad, no reason to try to change natural instinct, right?

there are evolutionary reasons why males may prefer a partner that has not had so many partners. Mate guarding, paternal investment and other concepts.

This is just textbook naturalistic fallacy. Something being natural doesn’t make it morally good. Would you be okay if someone raped you as long as they had an evolutionary reason for it? Of course not.

Also I’m not quite sure what is morally OK or good ethical practice about saying its fine for people to pursue shallow relationships as opposed to monogamous ones whether that is males or females.

1. Never at any point did I say “people should oppose monogamous relationships and should pursue shallow relationships”. This is a complete strawman.
2. If two consenting adults are not in a relationship and want to have sex it is perfectly ethical to allow them to do so and they don’t become any less valuable for doing it. This is really straightforward honestly.