something wrong?

My boy friend never wants to have sex. We can go weeks. He will fool around, but only get me off. He never wants to for himself. He always says he's tired, or it too close to my just ending my cycle, or whatever else. I'm starting to worry. I'm starting to feel like it's me. When I ask him he acts like I'm crazy for thinking any of the things I start thinking as to what could be the reason for it. Does anyone else have this issue? What were your outcomes? and what should I do? Nothing else has changed and we do live together.