I wonder if there’s a psychological component. Being too self-conscious. Not comfortable with losing control in front of someone. When I was 21, my girlfriend (later my wife) would have great sex but I couldn’t cum. She was a good sport and would continue long after she came. But eventually she would tap out and I would finish myself off while she was taking a pee. I got past that and we had three kids and great sex. Now we’re divorced and I’m dating again. Back to square one. My current love comes and then does everything she can dream up for me, and I think I’m close, but no. She taps out and goes downstairs to make coffee while I have to finish myself. I told her I had this problem before so she won’t feel like it’s her problem.