I'm really sorry to say that this is a terrible sign. Honestly, it's pretty common with men, but it could be a sign of a bigger problem. I assume that when you first met, it was mutual attraction, but now you're the one doing all the physical stuff? If he doesn't have that fire for you that he used to have and you want that fire, it might be time to take a break. I think I would suggest taking a break, although you need to be ready for the possibility that he finds somebody else. It's only been three years and this problem will just get worse. Remember, it's okay to move on. There are lots of fish in the sea.