Getting off

Last night I ended up having sex with one of my guy friends for the first time. I knew it was going to happen eventually because we've been talking on and off for months now. It finally happened last night and I was so into him. But now I'm just thinking he wasn't into me. It went about 30 minutes long and I got off but he didn't. I'm just thinking did I do something wrong or was he too nervous. Which of course he got a cramp (lol don't we all hate that) and stopped and he just didn't continue after that. I just can't help but think he wasn't feeling it. I'm thinking maybe it was because it was our first time together and usually the first time isn't all that great but I really don't know.