He felt beleaguered and blackmailed: Did they think he did not know what they had done for him, didn't they understand that it was for precisely that reason that he wanted to go now, before they had to suffer any more on his behalf? (5.134)
Following the ambushed effort to move Harry from Privet Drive to the Burrow, during which Mad-Eye died and George lost an ear, Harry feels frustrated about the idea that other people must make sacrifices for him, and isn't sure how to deal with it. After all, he's just one person, so why should all these other people risk their lives just for him?
"She's not an idiot, she knows it can't happen, she's not expecting us to – to end up married, or –."
As he said it, a vivid picture formed in Harry's mind of Ginny in a white dress, marrying a tall, faceless, and unpleasant stranger. In one spiraling moment it seemed to hit him: her future was free and unencumbered, whereas his… he could see nothing but Voldemort ahead. (7.52-53)
Here, Harry starts to realize what his decision to pursue Voldemort really means; it could be the end of everything he's ever hoped for or dreamt about.
And tears came before he could stop them, boiling hot then instantly freezing on his face, and what was the point in wiping them off or pretending? He let them fall, his lips pressed hard together, looking down at the thick snow hiding from his eyes the place where the last of Lily and James lay, bones now surely, or dust, not knowing or caring that their living son stood so near, his heart still beating, alive because of their sacrifice and close to wishing, at this moment, that he was sleeping under the snow with them. (16.92)
Harry's reaction at his parents' gravesite is to reflect upon their sacrifice – what was the point, when it just left him alone anyway? Again, we're asked to consider the cruelty of sacrifice; somebody's always hurt, even if they're the one being saved.
…shortly afterward he had set to work, alone, digging the grave in the place that Bill had shown him at the end of the garden, between bushes. He dug with a kind of fury, relishing the manual work, glorying in the non-magic of it, for every drop of his sweat and every blister felt like a gift to the elf who had saved their lives. (24.7)
Harry's grief at Dobby's death reflects his guilt and pain at the idea that others make willing sacrifices for him. It hurts more than anything else to think about the fact that those he loves, like Mad-Eye and Dobby, are ready to give up their lives for him.
"My brother Albus wanted a lot of things," said Aberforth, "and people had a habit of getting hurt while he was carrying out his grand plans. You get away from this school, Potter, and out of the country if you can. Forget my brother and his clever schemes. He's gone where none of this can hurt him, and you don't owe him anything." (28.43)
Aberforth bitterly notes the tendency for people to get hurt by Albus's schemes, even if they're for the greater good, and doesn't want Harry to willingly give himself up just to finish the path that good ol' Albus started him on.
"[Albus] told me I had to finish my education and he'd take over from my mother. Bit of a comedown for Mr. Brilliant, there's no prizes for looking after your half-mad sister, stopping her blowing up the house every other day. But he was all right for a few weeks… till [Grindelwald] came." (28.69)
We finally learn what happened to the Dumbledore family – it seems that young Albus was ready to sacrifice his early career to take care of Ariana. But his was not entirely a willing sacrifice, as demonstrated by his easy distraction by Grindelwald's charms.
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.
The Snitch. His nerveless fingers fumbled for a moment with the pouch at his neck and he pulled it out.
I open at the close.
Breathing fast and hard, he stared down at it. Now that he wanted time to move as slowly as possible, it seemed to have sped up, and understanding was coming so fast it seemed to have bypassed thought. This was the close. This was the moment.
He pressed the golden metal to his lips and whispered, "I am about to die."
The metal shell broke open. He lowered his shaking hand, raised Draco's wand beneath the Cloak, and murmured, "Lumos."
The black stone with its jagged crack running down the center sat in the two halves of the Snitch. The Resurrection Stone had cracked down the vertical line representing the Elder Wand. The triangle and circle representing the Cloak and the stone were still discernable.
And again Harry understood without having to think. It did not matter about bringing them back, for he was about to join them. He was not really fetching them: they were fetching him. (34.37-43)
There's only one comfort in this sacrifice – the Resurrection Stone. Harry uses it to call back his departed loved ones to help him through this terrible moment… it's the least Dumbledore could do to ease this decision.
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.
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.
"I resented it, Harry."
Dumbledore stated it baldly, coldly. He was now looking over the top of Harry's head, into the distance.
"I was gifted, I was brilliant. I wanted escape. I wanted to shine. I wanted glory.
"Do not misunderstand me," he said, and pain crossed the face so that he looked ancient again. "I loved them. I loved my parents, I loved my brother and my sister, but I was selfish, Harry, more selfish than you, who are a remarkably selfless person, could possibly imagine." (35.57-60)
Dumbledore, it seems, wasn't quite strong enough to sacrifice his future for his family, as he was asked to do – one of the reasons why he recognizes Harry as a better man. Harry's selflessness is remarkable; his choice to sacrifice himself is something that most of us wouldn't have been able to do!