Fred Weasley has six birthmarks on his back that stand out distinctly from the light smattering of freckles on his shoulders. He has a scar on the back of his left thigh from a fall from a broomstick at the age of four that he never told his mum about (and therefore never had treated). He's ticklish behind his ears and a spot halfway down his back, and if you brush one of those spots just right you'll get a high pitched yelp of a laugh instead of his usual guffaw.
Hermione Granger knows all this because she loves Fred Weasley and has spent a considerable amount of time learning the little things about his that distinguish him from his twin. The hidden aspects of his life that so few know. Secrets that make him her own. She stares at his photo on the wall and blinks away her tears.
Fred Weasley had birthmarks on his back. He was ticklish. She still loves him, but she puts that feeling aside most of the year. It's only on days like this that the feelings return. Her husband allows her the moment of emotional infidelity because he understands. He misses his elder brother as much as she, if not more, and can put aside his jealousy long enough to allow the grief to pass.
Ron Weasley holds his hand out to her and waits for her to take it. He'll give her all the time she needs but she stares only a moment longer before reaching out blindly and moving to join the rest of the family. They make their way out into the crisp spring air and moments later stand in front of a memorial that will never truly capture the sacrifices made by those who brought peace to the world, nor the pain of those left behind.