Boyfriend masterbating

I have been woken up by my boyfriend masterbating on and off for about a week. He does it in our bed while I’m asleep. It’s a lot and it kind of bothers me. I get uncomfortable and butthurt. I tell him that he can wake me up for sex all the time cuz I want sex too. He will go to bed with no sex then I’ll wake up a few hours later to him whacking it right next to me. It makes me insecure and idk how to approach it. The first couple of times I just pretended to be asleep and the last 2 times I caught him and had sex with him. He seems frustrated when I do. Any advice?