He's always hard, has this ever happened to you?

I've been seeing my boyfriend for a year and he's always hard around me. He's my first long term boyfriend. 
Even in public. We can be at a loud music festival and I look down at his pants and see the bump. We can just be sitting together on the train and he's hard. I don't have to touch him or anything and he's hard. There have been countless times I come over for breakfast and his dick is sticking up through his boxers. Mind you Im fully clothed and we're talking about the weather. Even if we have had sex 4 times in a row he'll be hard again after 30 minutes. He's 28 and In 24. So we're not teenagers. 
He says he's not like this with everyone. He doesn't masturbate maybe that has something to do with why he's always hard around me. Sex is great with him. I heard after the first year, couples tend to cool down sexual is this true? Just wondering cuz if we lived together maybe he would die from too much sex.