What to do about bad breath!?

I absolutely love my husband to death. But man he can have some bad breath often. It’s been like this from day one. At times it seemed to have gotten better but last night it was so bad.

I feel bad if I tell him. I don’t want to make him feel embarrassed. I have told him before and he gets so sad. I’ve even tried to push the mouth wash and special mouth stuff but it doesn’t last long. He’s a mouth breather especially at night because of how bad his allergies are.

I have no clue how to help without telling him. I know I’d what you be told if I had bad breath. What can be causing it ?? Does he need to see a dentist about it?