Did he finish digging her grave and then started digging another? That would be cool because he’s gone insane. Or was he working on only one the whole time? a little unclear.

I like how you keep what had caused this apocalypse vague, it’s a very personal account that branches out. The final two paragraphs are a lovely mix of despair and wishing and then that last line- chilling, and so sad.
Also you get extra points for the seed banks in Norway.

Dear Third Robot,
The first grave was finished before the story starts. The grave he starts digging at the end is his own.

aha. makes sense know that I read again… sorry bout that. My bad.