Ron couldn't pinpoint the exact moment he fell in love with Hermione Granger. Maybe it had been in their fourth year, seeing her at the Yule ball and seeing her as Hermione, rather than his best friend? Or maybe it had been in their sixth year, or fifth, or even third. Certainly by their seventh year he had fallen, hard and fast.
He couldn't even pinpoint the exact moment that he had realised he was in love with Hermione Granger. It had definitely been in their seventh year, he was sure of it. Was it whilst he was down in the cellar in Malfoy Manor, listening to her ear splitting screams, screaming her name. That night he swore to himself that when he got her out of there he wouldn't let anything hurt her whilst he still had blood in his veins and air in his lungs. No, it had been before that. He was sure of it.
He had been alone. He'd left his best friends and had no hope of rejoining them. But then he had heard it. Her voice, whispering his name. As soon as the tiny ball of light floated to his heart, he had known. Known what he should have known for years. He knew than that the light would guide him home, guide him to her. The Malfoy Manor incident had simply confirmed what he had felt that night.
He was sure that was it. The moment he had realised he was in love with his best friend. But that wasn't important. He didn't have to know the exact moment he fell for her, or the exact moment he realised what that feeling was. All Ron Weasley needed to know was that no matter how he had felt in the past, it was how he felt now that counted. If fighting in a war had taught him anything, it was that. He knew that right now, he loved Hermione Granger more than he'd loved anything in his life, and would continue to do so until his heart stopped beating. Hell, he'd love her even after his heart stopped beating.
Ron couldn't pinpoint an exact moment when he'd stop loving Hermione Granger. He couldn't pinpoint it because it was never going to happen. No matter what happened or what they did, nothing on earth, or beyond it, would ever make Ron Weasley stop loving Hermione Granger.