I have had this situation unfold twice.
The first: guy I went on a few dates with, we clicked but he had just gotten out of a relationship and wasn't looking for anything serious. I wasn't having much luck dating so I suggested we just hook up and leave it at that. It was not exclusive (though I didn't sleep with anyone else except for a one night group sex situation, just because I wasn't particularly interested in anyone else I dated during that time). We had sex once or twice a week for about four months. It was good in that he was very enthusiastic and made me feel awesome in bed, which I enjoyed. And I liked the way he tossed me around and explored a little kink with me. And we were genuinely friends and hung out some. But I didn't really orgasm and it started becoming clear to me that it wasn't because he found it difficult but because he routinely ignored my advice about it/apparently didn't care that much. It finally ended because we were having sex and he said "are you close?" And I sorta laughed slightly in surprise because we were in a position that would never ever ever make me come (I was on my back on the bed and he was standing pushing my legs back, if that makes sense). It was a playful laugh, not a mean one; we had that kind of friendship. I said no and he proceed to finish and roll off of me anyway.
He kept hitting me up but I couldn't bring myself to continue after he made it so apparent that he didn't care. At least have the courtesy to pretend you want me to get off and are just struggling to do it.
The second was MUCH better and cared if I came or not (and consistently helped me out on that matter) but his voice reminded me of my cousin and that weirded me out after a while. Plus I just got tired of casual sex in general even though it was good casual sex. We ended on a very friendly note and I told him to hit me up if he ever needed references.