Help idk why this happened

I was with my boyfriend and I was jerking him off he didn't seem into it when all of a sudden he came but didn't orgasm. He didn't realize he came untill it was touching his leg. Then we had sex and he's not sure if he came in me because again he didn't feel like he was coming but he went soft like he did the first time. So we waited half an hour then had sex again and he had big orgasm. Why couldn't he feel it?