When I was hearing this from my wife, all I could hear was "work harder." Once she dropped the bomb, the world of possibilities opened up for me. I suddenly saw all the options for things I could have done:
1. I learned about relationships -- I wish she could have given me "The 5 Love Languages" for instance. 2. I started taking anti-depressants. (Should have done it years ago). 3. I began treatment for an auto-immune disease (This one is tricky as it was coincidentally at the same time. But, it may be worth considering the possibility your husband has some problems). 4. I opened up to my family about the struggle I was having. All of a sudden I realized I had a resource who could help me. 5. I just started hoping that I could be a better person.
If your husband is like me he just has his head down and is trudging forward. He has given up on making it better and is just powering through hoping for better days. He loves you and he finds you attractive -- he just doesn't love life and therefore has no passion.