My husband goes through bouts of depression (not precisely the same as grief, I know) and it is still difficult for me to discern how to "help" him - especially because when he is feeling that way HE doesn't know what would help.
The tack I take now - I ask him if I have done something to upset him or if there is something that we need to talk about. If no, I ask him if there is anything that he needs/wants from me - physical presence, listening ear, soothing food or music. If no, I leave him alone and work on keeping myself happy (if his sad makes me sad then he feels sadder).
Sometimes doing nothing IS doing something.
Me: poly bi female, in an "open-but-not-looking" Vee-plus with -
MrS: hetero polyflexible male, live-in husband (23+ yrs)
Dude: hetero poly male, live-in boyfriend (4+ yrs) and MrS's best friend
Lotus: poly bi married female, "it's complicated" relationships with Dude/JaneQ/MrS (1+ years)
+ "others" = FBs, FWBs, lover-friends, platonic G/BFs, boytoys, etc.
My poly blogs here:
The Journey of JaneQSmythe
The Notebook of JaneQSmythe