My boyfriend and I have some of the greatest sex ever, but he usually jerks off when he wants to come (he's afraid I'll get pregnant) and it takes sometimes 20 minutes for him to .

And I'm just sitting there waiting. I try to do things while he jerks off to please him, but he says its hard when I do that

The other day we had awesome sex, but yesterday he couldn't get hard... and this happens more frequently than before.

Is it my fault? Or is there something wrong with him?