"'I came out miles from where you were. By the time I got back to that bit of riverbank where we'd been . . . you'd gone'" (ch. 19).
Ron was an idiot.
His fingers were streaming with blood, but he barely noticed the pain. There was a pain inside him much more present – much more real – than his stupid fingernails.
Harry and Hermione were gone. And it was his fault.
All of the fingernails on his left hand were missing. It was like a physical representation of what he'd lost – and how it had been his fault.
He wasn't whole if Harry and Hermione weren't there. He never could be whole without them.
And he clutched his wounded hand to his chest, crumpled to the ground, and wept.
Deathly Hallows, here we are! Ron, right after he escapes from the Snatchers. I thought the fingernails were a pretty accurate microcosm for how he must have been feeling.