I can't make him cum??

My boyfriend was a virgin when we started dating a few months ago. I expected the sex to be quick and that he'd finish early. But when we first started having sex, he couldn't cum at all, which I attributed to him being nervous. Everything was fine for a bit after that, he'd be able to finish. But now again I still can't make him cum, the last few times we've had sex he hadn't finished and I asked why and he said he was tired, but he seemed fine and had a lot of energy throughout the night.

He's able to finish with a blowjob but usually not sex.

He reassured me that it's not me, but when I asked him if he can finish with porn, and he avoided the question.

I feel like I'm not good enough. I feel embarrassed and gross.

It's either me, or he's lying about the amount of porn he watches and his masturbating habits. I don't know what to do. This is really taking a toll on me and I'm very upset.

Do you guys have any advice? Is this normal for men?