The chemistry of the romantic love bond isn't the same as the culture of romance. The former is universal, the latter a medieval invention.
If the sex act weren't degrading and humiliating, we wouldn't have to tell so many stories about it to redeem its sheer animal crudeness. It's a case of avoiding cognitive dissonance and feeling better about our necessary hypocrisy. Animals don't have to lie to themselves because they don't presume they're godlike people. We do, so when we're forced to act like animals in overt ways, that strains our self-image.
Indeed, breathing and eating are also animalistic, but they're not as striking, memorable, or gripping as sex, are they? The road to orgasm looks like the foundation of religious experience, which should be traumatic to religious people.
Everything we do has a biological component, because we carry it out with our bodies. But that's not the same as saying that everything is driven directly by biology. Most of what we do is driven by culture and by our antinatural creativity. When we walk around in suits and ties and when we sit at our desks and type away at our computers, we're not being especially biological. Likewise, scientific reason is an exaptation, not an adaptation.
Would most people characterize sex in blunt, physicalistic terms? Well, I'm going to be writing a follow-up article on the difference between lovemaking and fucking. The latter is more animalistic than the former, but both are liable to make us less existentially authentic.
My whole point is that we tend to tell stories to avoid thinking hard about unpleasant realities, so of course most people wouldn't think of sex as degrading. That doesn't change the objective fact that sex is a physical, animalistic act, whereas we don't like to think of ourselves as animals (because we eat animals for dinner, and we torture and enslave them and run them over with our car).
The dualism I'm talking about isn't metaphysical or theological. It's the difference between the natural and the artificial (not between nature and supernature). Again, most of the time we prefer to be living in our artificial, self-made environments, in our houses, cities, offices, entertainment complexes, cultures, languages, worldviews, and so on. We escape now and again to our secret practices, to our animal regressions, and then we have to live with the hypocrisy. That's what the fictions and myths are for.
I'm not suggesting we stop having sex. I'm suggesting we find the right story, one that's honourable and inspiring without being self-deceptive.