He NEVER c*ms during sex!!

Help! So I’ve been having regular casual sex with a friend and we have an amazing sexual chemistry. He likes a lot of what I do and is very attracted to me. We have sex multiple times in one night. I’ve had plenty orgasms with him but he hasn’t finished ever with me! I’m starting to wonder what is going on! I’m scared to mention it and make him feel uncomfortable but it’s been playing on my mind and I’m desperate to make him finish.

What should I do??