Sounds like my DH when he lost his dad.
I left it a while and made allowances for his grief but it got to the stage where it was affecting his relationship with our DD and I had no choice but to step in before it became irrepairable.
I went with him to the doctor who put him on snti depressants and told him to refer himself to crus for bereavement counseling.
The pills helped, he's still not right and has had the initial assessment but still not had his first proper session.
It was painfully slow even to get to this stage. Dad died June last year. DH went to the docs first week in January and he only had his assessment 6 weeks ago and still no sign of counseling starting.
It's early days for your DH and he is understandably struggling.
When I spoke to DH I grabbed him, hugged him, told him I loved him so much but that I could see how much he was hurting and that I knew he wasn't coping because of how he was treating us which wasn't like him at all. I told him we understood but that it was time to seek help and id be with him all the way.
I wish I'd done that sooner as neither of us appreciated that 7 months on and counseling still hadn't started. Doc said this was quicker than the Italk route.