Difficult ual health question on behalf of my boyfriend ?

Ok, well my boyfriend and I have a great life and I'm very satisfied. I would say however, that he tends to climax quite quickly. He does stop and take a breather sometimes! But he finds it really difficult to 'hold off'. We've been together for about a year and I always thought that after a few months things would calm down and it would be easier for him. Like I said though, I'm really happy and it doesn't affect our relationship - I'm just curious if anyone else has this problem or knows of reasons why this can happen? (Really sorry if I've offended anyone with this question.)