Jobless
Your husband doesn’t have to complain but there are ways to voice issues to superiors. Coming home at 4 is not normal. He’s not Warren Buffet. He needs to find a way to explain to his boss that he has to scale back a bit and maybe others should pitch in more. He won’t be fired if he’s as good as you say he is and as dedicated as you say he is. Companies don’t fire people who are willing to come home 4 am!