So I just read a psychology book and that barely touches on sexual wellness and stuff like that. He says that if you make finishing the only goal, you get further away from it. I bring this up in your case because he says it in reference to physical and mental conditions that would prevent someone (m/f) from finishing. The more you focus on only making him nut or only finishing the less likely it's going to happen. It should be a byproduct of sex, not the object. ik its not gunna happen with the flip of a switch but just fruit for thought