When Ron disappoints her, Hermione's face is, like, broken. Harry can see it in her eyes and in the way she pretends to be okay until she can't anymore. Harry's never really seen Hermione care so much about anything – not school, not this war. Ron means more to her than the entire war.
And then he leaves. Beyond being furious, Harry's broken too. The one Harry Potter would miss most, isn't that what Dobby said before the Second Task? Not Hermione, not Cho, not Ginny, no one else. It was Ron, no questions asked. And he never questioned it.
Hermione cries a lot at night. She never seems to stop. She might be crying in her sleep, Harry doesn't know. Sometimes he turns his face to his pillow and cries with her, silently, cautiously. Harry doesn't wear the locket but everything hurts anyway. He just wants his best friend back. He thinks Hermione wants to fall asleep holding Ron's hand, and that's why she grasps at the air throughout the night.
She says things in her sleep, things he probably shouldn't listen to. Things she shouted before Ron vanished.
Ron never thought he was important, Harry knows, probably assumed they'd forget about him when he left. Like he was never there. But everyone's broken without Ron, and everyone cries at night and there's no one to remind Harry of Ginny, and there's no Ron to disappoint Hermione in that way she likes. The way she's been comfortable with for years, that scares her when it's gone the way it's been gone most recently. Replaced by offering her the couch and letting her take care of him without complaints; by smiles and hands and unconscious name-murmuring, little balls of light and leaping into arms, breathing each other in and out like air, only more important.
Because Ron comes back with a speech he didn't think out thoroughly and she stares at him with a mixture of hate (because how could he think it was even possible to fix the heartbreak of losing him) and love (because how could she not? After all these years and all this change and everything she's ever wanted how could she not love him?) and confusion (because how could he not know?).
And then they make up and all those smiles and all that breathing each other in, those come later. Not much later, but it takes some time.
When Ron makes her happy, Hermione's face is like the goddamn sun. Everything about her is bright and shining these days. Maybe she's always been like that around him, Harry just hasn't noticed.
He looks to his left and there's Ron, just like always. Except now he holds Hermione's hand and kisses her in the dark and even when it's morning, and they have a family and Harry's part of that family.
Family is all Harry's ever wanted and he has it, full and happy and certainly not lacking in love. There's so much goddamn love in this family.
And, most of all, Harry wishes he'd been watching them the whole time. These two and their ridiculous, undeniable, omnipotent love is more important than any other kind of magic he's discovered along the way.