Oftentimes, we humans find other humans sexually attractive and it comes with the notion that this is due to their physical traits, whichever kind of criteria the other person prefers. Though it isn’t within the “conscious” state of mind, this isn’t actually what’s going on in the person’s thought, in a deeper sense. The solace found in sexual intercourse is due to its tendency to feed a mental hunger that we don’t always consciously notice, and this is the instinctive and natural desire to breed. Yes, breeding, even if the persons never actually intend to have children. So basically, sex is more “subconscious” than it is “physical”, although of course, the latter plays a major role. It (sexual desire) is instinctive as it is naturally for the purpose of survival of the species, ergo the natural demand for it. It has been “implanted” in our brains by evolution, which is also partly why it is such a desirable concept. We can easily compare the instinctive concept of sex to the instinct to eat. It is ultimately for serving a purpose of species survival, it is a form of psychological sustenance, while consumption of food is physiological. The pleasure of sex all boils down to feeding that hunger.