The break-up

Harry looked at Ginny, Ron and Hermione: Ron's face was screwed up as though the sunlight was blinding him. Hermione's face was glazed with tears, but Ginny was no longer crying. She met Harry's gaze with the same hard, blazing look that he had seen when she had hugged him after winning the Quidditch Cup in his absence, and he knew that at that moment they understood each other perfectly, and that when he told her what he was going to do now, she would not say "Be careful", or "Don't do it", but accept his decision, because she would not have expected anything less of him. And so he steeled himself to say what he had known he must say ever since Dumbledore had died.
"Ginny, listen . . ." he said very quietly, as the buzz of conversation grew louder around them and people began to get to their feet. "I can't be involved with you any more. We've got to stop seeing each other. We can't be together."
She said, with an oddly twisted smile, "It's for some stupid, noble reason, isn't it?"
"It's been like . . . like something out of someone else's life, these last few weeks with you," said Harry. "But I can't . . . we can't . . . I've got things to do alone now."
She did not cry, she simply looked at him, "Voldemort uses people his enemies are close to. He's already used you as bait once, and that was just because you're my best friend's sister. Think how much danger you'll be in if we keep this up. He'll know, he'll find out. He'll try and get to me through you."
"What if I don't care?" said Ginny fiercely.
"I care," said Harry. "How do you think I'd feel if this was your funeral . . . and it was my fault . . ."
She looked away from him, over the lake.
"I never really gave up on you," she said. "Not really. I always hoped . . . Hermione told me to get on with life, maybe go out with some other people, relax a bit around you, because I never used to be able to talk if you were in the room, remember? And she thought you might take a bit more notice if I was a bit more—myself."
"Smart girl, that Hermione," said Harry, trying to smile. "I just wish I'd asked you sooner. We could've had ages . . . months . . . years maybe. . . ."
"But you've been too busy saving the wizarding world," said Ginny, half-laughing. "Well . . . I can't say I'm surprised. I knew this would happen in the end. I knew you wouldn't be happy unless you were hunting Voldemort. Maybe that's why I like you so much."
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Harry Potter and the Half-Blood Prince Chapter Chapter Thirty: The White Tomb