The reverence aspect is conferred by culture. And not all humans have the kind of oxytocin response you’re talking about with their chosen sex partners. In fact, enjoyment of sex has a lot to do with the culture one is raised in.
But yes, certainly I agree that there are aspects of sex which are not culturally learned. Being that physically close is dangerous. It requires trust. Not just trust that the other person isn’t trying to hurt you, but also that they’re actually interested in you, not just getting off themselves, and that they’re not being irresponsible with regard to diseases or pregnancy.
