No action in bedroom...

Over the last few years my now husband and I have been having issues in the bedroom. The issues lay mostly with him, in the sense that he's never in the mood for sex. Right now we are on month 9 without sex. He says that the problem isn't me. But in the past I have had my suspicions. Then I think, if he didn't love me he wouldn't have married me. (we've only been married a year). So my question is, what could be wrong? Low T? Depression? We have talked endlessly about these issues but most of the time he shuts down. Just looking for some advice.