Even without children, companionship, intimacy, and yeah, love, have tangible emotional rewards.
If you have never felt these feelings because you're young and haven't met anyone interesting yet, that's one thing. If you're older and just don't feel these feelings towards others, then you might want to talk to a professional about that.
If you have never felt feeling of being disillusioned then it is because you are not old and haven't really found out true nature of your relationship.
Highly recommended experience: Go to your local family court on a nice afternoon and sit back and relax for few hours. One of those people there is your neighbor who was just until yesterday happily married and now losing his home and worried about how he would pay alimony and see his children more than twice a month.
No one gets married thinking they would ever divorce. 50% of them divorce nonetheless.
Or I could just spend the day with my wife and kids in the park...
Doing such an analysis and coming up with a different conclusion than the (current) norm shouldn't be grounds for him needing mental health services.