There are men who can't balance job and family activities and thoughts. Some men feel satisfied having simple married life by just providing for the family's material needs while exerting more effort to be efficient at work. Sometimes they even bring home thoughts from work which make them look like robot at home.

Guessing is not any better than having an open minded conversation. Try to find interesting topic for him to talk about, something that makes him smile then transition to a point where you bring back your pre marital memories specially the ones that made you happy and got more attracted by him. Try to mention all memories that you saw him laugh. Then encourage him to discuss the current situation. Check out this link, it would be nice if you print and place it where he can see it: 6 Obstacles to Building a Healthy Marriage | Psych Central.

Wish you the best.