We've had a couple of lovemaking encounters recently that have emphasised for me how difficult change in this area is.
On the first occasion, we failed to agree in advance how our session would 'end'. Things went well, initially. After half an hour or so of relative inactivity, I experienced an extraordinary merging moment, where I could no longer sense the boundary between my wife and myself. This followed a series of involuntary butterfly sensations of gurgling and contracting in and around our genitals. It felt supremely peaceful and I could have remained like that indefinitely.
However, I also felt I could go on indefinitely, and serve as required, and an underlying sense of this nagged at the back of my mind like a pressing appointment. I asked my wife if she wanted to continue and she nodded. It then became a matter of pride to assist her to orgasm while refraining myself.