George tries not to think about his twin too much.
Of course, it's almost impossible not to.
He knows that if he thinks about Fred too much, he won't be able to stay sane. Even seventeen years after the Battle of Hogwarts and Fred's death, George still feels an ache every time he forgets, every time he turns around to share a joke with his twin and realises that there's nobody there. No matter how much he knows he can't linger on the pain, he's still human and he still needs to grieve. So he grants himself a reprieve. On May 2nd, every year, George spends the day remembering his twin brother. Harry has asked him every year to go to the official memorials, but he can't face it. He just can't take all of the people who barely knew Fred in floods of tears. He needs his one day a year, when he allows himself to grieve, to cry, to wonder what would have happened if he had been beside Fred when he died. Would he have been able to save him?
He'll never know now.
Four other people feel (almost) the same pain that cripples him. Mum becomes quiet on May 2nd, her usual motherly chatting and fussing absent. One year on May 2nd, George decided he would try and take comfort in his mother, so he went over to the Burrow to find her. He opened the door to the kitchen, only to find her crying over an old, threadbare Weasley jumper with a faded 'F' emblazoned in the middle. He didn't know how to explain to her that he had the same hurt bottled up inside of him, that he missed Fred just as much as she did.
So he closed the door and went back to his house alone.
Dad doesn't change too much on the anniversary, on the outside, at least. If you didn't know him, you wouldn't even realise he was sad. George knows better, he sees the haunted shadow that only appears in his father's eyes when he's remembering his dead son.
Percy can barely function on May 2nd. George knows that he's filled with overwhelming guilt that he survived and Fred didn't. The worst thing is, George is never able to bring himself to comfort his brother because there's a part of him that is furious at Percy because he didn't save Fred.
Angelina, his amazing wife, is completely destroyed on the anniversary of Fred's death. She knows that it's George's one day of sadness, so she spends the day at a friend's house. George knows that if Fred had lived, she would have almost certainly married him instead. George tries so hard not to think like that, but on May 2nd, he doesn't need to censor his thoughts.
Maybe one year, he'll spend time with the people who are grieving just like him. For now, though, he will be alone in his sorrow for his missing reflection every May 2nd.