What's wrong with my body??

So I'm with my Boyfriend of 2 years now. We used to date in highschool. It ended poorly. That was back in 2009. So here we are. I find myself having no sexual interest. Sometimes it's there, but, as fast as it came it goes. What is wrong with me? I love him and as much as I'd love to please him physically I just .... I'm not into it. Does anyone have some suggestions? I know 2 years is not a very long time just so everyone is aware but it feels like we've been together forever. Not in a bad way. Just like its been a lifetime and we know so much about each other. More than anyone else could know us.