Honestly, it doesn't sound good. He may have resigned from the relationship along time ago. But all the outside opinion in the world is not equal to honest open dialog between the two of you. You need to ask him where he is at, permitting him to be completely honest, and be ready to hear things you may not want to hear. He has likely been carrying a lot of resentment for the last six years and may be paving his way out of the relationship. Then again, that may not be the case, but you can only guess and feel miserable unless you talk to him.