Well hello! Let me try and give my input and see if this could be the answer you were looking for. As the 18 year old guy that I am, I used to be the same way.. For me.. It was inexperience and a bad teacher. I had to reteach myself differently. The main reason I did it was simple.. Whats the main thing we all have in common when it comes to cumming? Consistency. What better way/easier way to be consistent than to drill you? It's hard giving you what you want, and how you want it without any clues besides the movement of your body. Not all guys know the language of the female body. I guess I'm just lucky to have cracked it at such a young age even though it won't help me much. I don't want more than 5 sexual partners in my life time. That's just not who I am. Oh well :P. I know it's lame, but try talking to him about it.. Any real man is aiming to please his lady. Plus it's more fun to make your girlfriend cum because it's so much easier to make us guys cum :D it's like a game that I want to win multiple times before you even get the chance to touch me.