Not a good sex story... sorry everyone. But I still need help!

Ok so this guy that I’ve been sleeping with for a while now usually cums within the first 20-30 minutes, sometimes even 15. But the last time, we were at it close to 3 hours and he didn’t cum once! We tried a few different positions, and I gave him head (also usually works very very quickly) and still nothing!! And then last night, again for a hour, and nothing from him (I came both times lol). After the first time i didn’t think it was a big deal, but after last night, I’m starting to think it’s my fault. I don’t know what to do... any suggestions?