Quiet
Sometimes Harry just needs time to think. Time away from the kids and Ginny and Ron and Hermione and all of the Weasleys.
He just needs some time to be himself, no worrying about how to show he loves Ginny, or facing Hermione's pestering when he's too quiet. Ron's usually the best one to go to when he's feeling like this, no awkward questions just a drink with his mate, but today Ron isn't the one who can help.
Sometimes everything happening around him just slows down and he feels like a ghost, like he has gone back all those years to the Forbidden forest and that conversation at King's Cross. Even now he hears the voices from the veil calling him in, come back to us.
For all of his childhood he has always been alone, first being ignored or victimised by the Dursley's then at Hogwarts. Yes, he was surrounded by people but when you're the "Boy-Who-Lived" no one really wants to know who you are. Although Ron and Hermione were there they never understood the pressure to always be perfect or the fact that he had to become an adult too soon. Perhaps they understood a little by the end of the war but the solitude he feels can't be felt by them.
He doesn't begrudge them for their lack of loneliness he's just envious of it. While each one of his friends has experienced a loss, the Weasleys lost Fred and in some ways George, Hermione lost her parents in an unexpected plane crash and Neville never knew his parents, it is not the same way as Harry. He lost each and every parental figure he had, first his parents, then the Marauders and Dumbledore and finally Snape. He knows that Mr and Mrs. Weasley, Arthur and Molly, are there but when they already have six other kids to care for he can't help but feel like he's intruding. Teddy is probably the only one who understands but hopefully his understanding only covers a fraction of Harry's suffering as with his love and large adopted family he didn't have to spend 10 years of his life being constantly belittled.
Maybe it is too self-indulgent for him to think like this but when you've lived life with so much silence to be thrust into a word with loud-mouthed redheads and constant staring and whispers, it is impossible to be around the noise constantly. It was a wonder that he never suffered from panic attacks.
Morbidly it is only at his parents graves that Harry can escape from the noise. Apart from occasional relatives visiting their own relatives, he is left alone. One day he'll bring Ginny with him to this spot but right now this is still his space and his piece of quiet. Harry thinks to himself that the date certainly makes his location ironic.
After an hour of standing in the same spot Harry finally begins to move and prepare himself to apologise to his wife. He knows she understands that sometimes he needs a little space but it's never polite to run out of your own birthday party.