Waiting. He was always waiting. He'd already buried one best friend and now the other will follow. There was nothing he could do or say. There was no Harry without Hermione. Ron witnessed the beginning and now he must accept the end.
Seriously. I went through nearly a dozen tissues while reading this fic, but it's so good. It's one of the only Harry/Hermione fics I've read that treats Ron like a real, three-dimensional human being (and not even canon does that!), and makes me truly like him.