I think that what makes sex exciting is really the sense of someone allowing you into their life. The backdrop to sex is loneliness, a feeling of our unacceptability and alienation from others. You can analyze almost any so called sexy situation through that lens. Eroticism is really the physical manifestation of psychological excitement. In oral sex, for example, again, why would that be particularly exciting? It's exciting because it's permission. And this is a vital corrective to haunting feeling of loneliness, which pursues us all the time.