Calling sex “natural” doesn’t help your case since it concedes my point about hypocrisy. Unless you’re advocating for ancient Greek-style Cynicism, you should recognize that most of what we do us unnatural, as in artificial rather than wild.
I agree that sex is usually part of a happy life. But I think our intellects tend to make us discontent, so that happiness is a more fitting primary goal for the duped masses of self-absorbed consumers, not for intellectual elites. The more we know, the more we sacrifice our chance at contentment in the pursuit of certain duties. Discontent breeds great art, for instance.
The standard of happiness is indeed childish, given the state of the world and our existential situation. Hypocrisy enters the picture because childish folks have the potential to grow up.
I’ve written about happiness in the articles below: