He cums so fast

So my boyfriend and I are about 17 and we’ve had sex multiple times. Every time, he cums in 2 minutes, no exaggeration. The only time he didn’t was a few hours after our first round, it took him like 10 minutes. I just want to know why this is happening?

I’ve given him head and he’ll finish within 15 minutes or so. If I do it a second time it’ll take him at least 30 minutes. So why does he cum so fast during sex?

I’m the first person he’s had sex with so I understand that it won’t last long. But 2 minutes?

I’ve had sex with one other person before him. I understand everyone is different.

I just want to understand why this happens. It’s not a reason to leave obviously, I just want to help us.