rejection ?

So my boyfriend is on a medication that has a very common side effect of killing sex drives. I knew that ahead of time and we joked about it. But now that he's been on it for awhile, I can start seeing the effects and I know what it's from, but I can't help but getting really deeply emotionally upset when he doesn't want to have sex with me. He doesn't see it because I hide it from him. I know he can't help it, but still.