This was a wonderful thread, thank you. I would like to share my own personal experience that really clicks with all this information here.
When I met my ex, sex was never "goal oriented" for me but rather a wonderful chance to bond with her because it was something I had never experienced before. I've rarely had so much as a friend, never mind a lover. In fact, I would tell her at times: let's just cuddle instead, or watch a movie, or just spend time together. It lasted for about 6 months but then I caught her being flirty with her ex and lying to me about it. I confronted her then she apologized and she said wanted to change. Then it happened again and she lied again.
I remember the realization I reached that this relationship was not going to work and I'm ashamed to admit I did not end it there like I should have. I chose to ignore it because I didn't want to be alone again. After that decision, sex certainly became goal oriented and much more frequent. It got to the point where we slept together every time we saw each other, which was nearly everyday. Sure enough, the relationship tanked from there. We both became very irritable and would fight every two weeks at a minimum, break up, get back together and repeat the same mistakes. In the end, she was telling me: let's just cuddle or watch a movie instead.
Honestly, looking back I understood what I was doing. My twisted excuse was that if I kept her satisfied, she won't feel the need to flirt with anyone else. But in reality, I was just ignoring the problem and covering it up with dopamine. And this excuse ultimately accelerated the end of our relationship regardless. It does fill me with shame to look back and see how much I changed and what I did to her to escape my own fear. Essentially, I used her and it's a terrible feeling. If I would have ended it, I might still have a friend today. But, there is a lesson to be learned from everything, and our time together taught me the importance of understanding the body and mind so I can assure I don't hurt people again. This will be another book on my list, if only I would have discovered it sooner! Thank you.