I would say that one of the things that I enjoy most about sex is knowing that my partner is about to ejaculate. I have found that it often tips me over the edge into having an orgasm myself when I am getting close. For me there are multiple factors that contribute to why I enjoy it so much. Firstly, I'm a strong believer that sex should be equally enjoyable for both parties, and each should be trying their best to make it pleasurable for their partner. Knowing that he is receiving pleasure from me to the extent that he is going to have an orgasm from it is a significant turn-on to me. It boosts my ego and scratches an instinctive itch. If he makes some sounds to indicate that he is getting close to climaxing himself, or is actually having an orgasm (like grunting and groaning), then that makes it even more of a turn-on. The last thing for me is that I actually find it quite satisfying to know that I've been filled up, so to speak. I don't have any hang-ups about it. It's probably the thing that I enjoy the most about intercourse itself.
I wouldn't feel comfortable asking anyone in real life about this so I'm grateful to have the opportunity to do so on MN. My friends probably think I'm a prude who doesn't enjoy sex at all, and would no doubt be flabbergasted if I made the slightest mention of it. 😄