Used to be, in some sections of some societies, that saving sex for marriage was for both parties’ protection. If someone was going to eventually make that decision that “you’re not my type”, they didn’t get to test-drive you all the way to Prague and back: a man was expected to have enough self-knowledge to know (or at least make a reasonable guess) that it wasn’t going to work out before he polished his torpedo below your decks.

It was, at least officially, considered scoundrel’s behavior to have sex and then return someone to the shelf to go shopping again.

That was only ever officially true, rarely in practice; and it didn’t last for good reasons. But consider how things have changed.

Dating is at least as much about having sex as it is about finding a life-partner now. Women are now entitled to the same level of self-determination: they also are entitled to sex and to consider and reject a partner based on any criteria that seems good to them.

That’s arguably progress.

Is that “okay”?

You’re experiencing the down-side after having experienced the up-side. When people start selecting, they’re capable of rejecting.