Need advice

So I just started dating this guy and he's one of the sweetest, most caring guys I've ever met. He makes me feel like the most amazing person ever. The other day we had sex for the first time and it was horrible. Neither one of us could get off no matter what we tried. I'm used to it not happening for me, but the fact that actual sex with me couldn't do it for him and he ended up doing it himself to finish really hurt and I've felt so insecure and unattractive since. He's 21 and I'm 18 and we just entered this relationship, so I feel like we shouldn't be having this problem at all. I've never had a problem like this in the past, if anything, the problem was them finishing too quickly, not not at all or having to do it themselves. When I talked to him about it he said it had nothing to do with me and that he thinks I'm incredibly sexy and I was the best sex he's ever had, but he thought that maybe since he's so used to doing it himself and knows what works, that's why he couldn't. I feel weird having to try to think of ways to "spice things up" already. He should be crazy about me and satisfied with just me rn. I'm scared that if things already started this badly, sex in our relationship is gonna be so forced and masturbating is the only way either one of us will be able to get off and I don't want that. We should both be happy and satisfied. Any advice?