1. Definitely seek counseling.
2. Is he suffering from depression? Some of what you say he says and does sounds like symptoms of depression.
3. I disagree that marriage is 50/50. I like what Dr. Phil says, it's 100/100. Spouses have to put everything they can into maintaining the relationship. The courting isn't over once you're married, it goes on for the rest of the marriage. You have a need and he needs to put everything he can into filling that need. That might be counseling or medication or both or whatever, but he needs to put in the effort to maintain your relationship.

(And age is just an excuse. I'm 41 and have almost the same libido I had when I was 25.)