And my Grandpa is, like, the best guy ever.
What's Grandpa say? If he says "it's okay" then it's okay. In my book anyway.
Hope that doesn't come off as me being a giant ###. I get the "you go to the funeral" @#$!....to a degree. In general, they idea of them is pretty morbid. You hang around staring at a corpse. Much bigger fan of wakes. I want to be cremated, mixed with the ashes of my wife/dog if they went first and then fired out of a cannon. Screw having everyone stand around ogling my husk(although, who could blame anyone? I'm sort of hot and grow hotter with every single year).
If Grandpa is truly okay with you missing it, then it really boils down to how you'll feel in a year if you don't go. If the answer is "sort of ####ty" then you go anyway.