Need some opinions

Hi. I’m having sex problems with my boyfriend. He’s my first and I’m his first. We’re both 18. Our sexual chemistry is great, especially with foreplay and oral sex. But the times we’ve tried to move on to vaginal sex, he gets soft and it’s impossible to get him inside me. This has happened 3 times now and he says he’s nervous and proceeds to cry after that. We tried yesterday, but it didn’t happen and I got up thinking there was something wrong with me, but apparently, it’s not. He’s the one that always starts and proposes to have sex, but then boom.

If you’ve ever been through something like this, what did you do about it?