Harry Potter and the Deathly Hallows
How we cite our quotes:
He could not bear to look at any of the other bodies, to see who else had died for him. He could not bear to join the Weasleys, could not look into their eyes, when if he had given himself up in the first place, Fred might never have died… (33.13)
It's come down to the moment of truth – Harry is faced with the necessity of his own sacrifice. Again he wonders how he could have let all of these people he loved die for him – and there's no answer to that question.
Finally, the truth. Lying with his face pressed into the dusty carpet of the office, Harry understood at last that he was not supposed to survive. His job was to walk calmly into Death's welcoming arms. Along the way, he was to dispose of Voldemort's remaining links to life, so that when at last he flung himself across Voldemort's path, and did not raise a wand to defend himself, the end would be clean, and the job that ought to have been done in Godric's Hollow would be finished: Neither would live, neither would survive. (34.1)
After witnessing Snape's tragic story, the truth becomes clear to Harry: he has no choice but sacrifice himself, something that Dumbledore ensured. The only option to save the rest of the world is to give himself up.
If only he had died like Hedwig, so quickly he would not have known it happened. Or if he could have launched himself in front of a wand to save someone he loved… He envied even his parents' deaths now. This cold-blooded walk to his own destruction would require a different kind of bravery. (34.4)
The sacrifice demanded of Harry is indeed a horrifically challenging one – he alone knows what he must do, and it's up to him to resolve to do it. It's not an act of passion, but one of calculated, "cold-blooded," and controlled will.