He knows. He's always there when the people he cares about die. Never soon enough to stop it, always just in time to hold them as it happens. It's a pattern he had hoped that he'd broken... but holding Ami as she fades away tells him he hasn't. He doesn't have any words, even though he feels as if he should say one last thing. Instead, he holds her body until there's nothing left to hold. Don't tell him it's a dream. Waking won't change anything.