Not sure if you are into it or he is, but have you thought about tying him up? Maybe know you have all of the power will let your brain stay there and feel in control. Just a thought. Kind of kinky, but lots of people do it.

Or maybe start smaller. Maybe instead of full out sex maybe you let him use his hand to give you an orgasm, or maybe put your hand on top of his to show him how.

Possible oral sex. I don't know at what point you start to zone out and not be there, but I would think if you start working on it and focusing on what it feels like,and you feel safe you may get better at enjoying sex.

I hope you can find a way to work things out. Sex is a wonderful thing, and is difficult when it is not happening between two people who care for eachother and at least one of them wants sex. Keep your spirits up. You can make this better.