We haven't been intimate for 3 weeks!?

I realised the other day, it's been 3 weeks since me and my partner have been intimate! I knew it had been a while, but didn't think it was that long. I don't know what to do...I know he isn't cheating, I'm at his place most of the time. He's had some...emotional issues (depression etc) and over time has become less affectionate, even stopped kissing me pionately. But the lack of intimacy is just about the final straw for me. What do you think is going on here? A complete lack of interest in me? Do you tink he needs space or what?