I enjoyed both of my proms but I had the same date both times and we were very good friends and had been for awhile. I only had three or so friends in high school but this one was one that I hung out with all the time so it was not awkward at all for us to go to prom together and we had a good time.
As far as your situation, I am glad you are going to ask him. If he says that prom might not be something he wants to go to then of course you should respect that but if I were you I would ask and of course make your intentions and where you are coming from very clear. He might say "no thank you" but then maybe he'll say "yes". And either way I am sure he will feel good that you asked. I wish you the best.
_________________
"I'm bad and that's good. I'll never be good and that's not bad. There's no one I'd rather be than me."
Wreck It Ralph