It comes as something of a surprise, receiving a real letter from Ron. Over the years, Hermione has gotten used to his frustratingly short, scribbled attempts at responses. Things change.
He's staying at Grimmauld Place until they can find a new headquarters for the Order. She shivers, imagining this. After Hogwarts, she's no stranger to ghosts, of course, but the idea of being there – she thinks she'd always see him, in darker corners or dim light. Perhaps shadows of a person can't be easily erased.
She's never quite been in the position to know before.
Ron is brave, she decides, and signs her letters 'love Hermione' instead of 'love from.' It's something small, but not quite insignificant.