The 5 stages of grief are necessary to complete before a survivor learns how to manage it and can thus be considered recovered.
That is why the first year or two of grief is the most crucial.
During this time, Ws often battle guilt, depression, and anger all at once.
He feels guilty for being alive while his LW is dead.
Meantime, try not to take his behaviour personally.
I know this sounds odd since you probably feel like the target of his angst, but please understand that a lot of his feelings are subconscious in nature (he can't help it) and perfectly normal for every W.
It is healthy for a W to walk every grief stage completely, so the last thing you want to do is to stand between he and his grief work.
It is beneficial and cathartic for W to be able to talk about his feelings.
He no longer feels worthy of the wonderful love the GOW brings, so he begins to withdraw from her.
The best thing you and W can do from this point forward is to really learn how to communicate effectively..often.
Although I caution GOWs NOT to play the grief counsellor, there are things you CAN do to bring grief to the surface.
Though these episodes apepar to come out of nowhere, there are usually signs: Holidays and death anniversaries are common grief triggers.
The magnitude of what he is feeling is just as confounding to him as it is to you.
If this is not something you think you can handle - and it would be OK if you didn't - then I recommend urging W to attend Bereavement Recovery classes, or seek counselling wit a qualified grief therapist.