L.N.
I would suggest that instead of asking him to help more, you approach it as a problem that you would like his help in solving. Maybe he sees this as temporary. Clearly when you've brought it up before, he feels criticized and underappreciated (even though that's not what you're trying to do). So I would try a different approach - I would guess that he isn't thrilled about having to work all the time. It's very hard to have boundaries when you're the owner of a small business - my partner owned one for a few years. We had to establish some parameters - like she wouldn't take phone calls after a certain time, no phones at dinner, etc. There has to be time that is work-free where you get to enjoy each other as a family, and where you both feel appreciated and that the balance of work is fair.