[Azure.]

Healing from loss takes time. Going to dinner probably brought back memories for him, as did going through his grandfather's old things. Anyway, I don't really think there is anything you can do that would take away his sadness. It is a natural part of grieving and only a state of acceptance brought about by his own mind can help him. However, the best thing for friends and family of someone grieving can do is to be there for them. I would suggest making sure that your boyfriend knows that he can always come to you when he wants to talk or when he feels sad. Support him as he goes through rough times and let him know that things will get easier.