My boyfriend watches porn.... A lot.

We are both in college, different towns. So we don't see each other as often as we'd like, however we make it a point to be together at least once a month if we haven't been able to throughout different weeks. We've been together for 3 and a half years. (Started dating during highschool). We're extremely happy together, and the sex is great! But.... Is there a reason that he watches it so much? I wouldn't say he's addicted, but it's more often than I would expect. He says it's not me, so what is it? 
RESPONSE: Thanks guys for the answers! It's not that it bothered me he watched it, cause I watch it too, it just seemed like it was QUITE a bit. Although, if it's just his way of dealing while we're apart, that is fine by me! I was just worried I was missing something! ☺️