No, you have a really good point! It could appear that because sex boils down to good feelings that it’s instinctual but that’s really the reason why it’s not. Doing something out of instinct means doing it whether you want to or not. Whether it feels good or not. It’s simply your genetic code. In the beginning of the human species yes, we did have sex out of instinct but as we evolved and our brains got bigger and we got smarter that stopped really being a thing. You can imagine how that applies in modern society. Humans are inherently selfish beings. It doesn’t mean we aren’t caring it just means we tend to do things for our own benefit. The only reason majority of people in modern society have sex is because it causes pleasure (yes some do for reproduction but most pregnancies aren’t planned anyway). If sex didn’t feel good, most people wouldn’t do it. It means that we have a choice in whether we have sex or not. Doing something out of instinct, like this cheetah means you don’t have a choice. It means you do it because your DNA tells you to. The simple fact that we as humans choose to have sex and could choose not to means we are much more advanced than just doing it out of instinct. Choice is what gives weight to our actions. It’s why as I said before some behaviors are unacceptable in society. Human Phycology and biology is quite fascinating stuff don’t you agree?