When my friend committed suicide it really helped for me to just have people there to listen. They couldn't make the pain go away or the feeling that I should have done more, intervened, seen how deeply disturbed he was. So I just needed to talk when I needed to and be left alone with my thoughts the rest of the time. Then again, everyone's not me.
He's going to have to come to grips with this himself. He's grieving and moving through the process. That's a good thing.
Moving to sadness is ok. That's not forgetting, it's missing her and possibly even forgiving her. It's reliving the memory of her.
I came finally to view funerals as a celebration of life. A closure. Something to give the living so that they knew the person was gone. And it's a great way to wrap up memories, talk about them with people of a like mind, and honor someone's life. Maybe you can get him to talk about the good times they had together.
I don't know. Grief is very personal.