Dumbledore was afraid that Harry may repeat his youthful sins of searching the deathly hallows for wizard dominance. he was afraid the untimely information would damage Harry's motive to destroy voldemort. moreover Dumbledore wanted to destroy the wand's power by planning his own death.
Why did Dumbledore not tell Harry how to destroy the Horcruxes? The reason that Dumbledore keeps his knowledge about the Horcruxes secret, (and presumably this is the same reason he did not tell the Order), is because he did not want the word to get around that he knew so many of the Dark Lord's secrets.
Why exactly did he do that? Dumbledore ignored Harry because he was afraid of the strong connection between Harry and Voldemort. He was scared that Voldermort might be inside Harry and he wanted to keep the decisions of The Order of the Phoenix a secret.
He has grown afraid of Harry's connection to Voldemort. Perhaps Voldemort, knowing Dumbledore's love for Harry, would possess Harry and provoke Dumbledore to kill him. So, Dumbledore attempted to avoid Harry throughout Book 5 for Harry's own good.
The reason Dumbledore wanted Harry to know about the hallows was because harry was likely to find out about them anyway (since one of the Horcruxes was a hallow - which Dumbledore needed Harry to have to complete his quest - and Harry owned another Hallow).
He does not find out when he realizes Harry's scar first starts hurting him. Dumbledore and Harry do not really talk about the pain Harry experiences in his scar until the later books, but it's sort of generally accepted that Dumbledore knows about it.
Draco Malfoy's mother Narcissa was cold, cunning and devoted to the Dark Lord. But she was also a mother, which meant she was willing to risk everything to make sure her son was safe. When Harry survived Voldemort's Killing Curse for the second time, Narcissa pretended he was dead so she could get to Draco.
Dumbledore knew that destroying Voldemort's horcruxes was the only way to truly defeat him. He believed that Harry was the one person who was smart, courageous, and perhaps lucky enough to find and eliminate all the horcruxes.
First of all, Dumbledore didn't reveal the secret of horcruxes to Snape because he didn't find it necessary. It wasn't his style to let out unnecessary secrets to people. Making horcruxes to fight horcruxes wasn't the plan.
He didn't block it. He enchanted a statue to jump in the curses path to be hit instead of the curse hitting Dumbledore. There is no way to block the curse - otherwise countless people could have easily been saved. The Abada Kedavra has no counter, cannot be blocked and is irreversible.
In Order of the Phoenix, Harry has to deal emotionally with the murder of Cedric and the return of Voldemort while working through the events he is experiencing at school. Harry's anger is a natural reaction to those events. He's not superhuman. He has been through a lot and his anger isn't permanent.
Dumbledore is trying to ascertain whether Harry will be entirely focused on the tasks that Dumbledore has planned for him throughout the year. Being in love might cloud Harry's judgement, or cause him to split his time and energy between a partner and getting that memory from Slughorn.
Because Snape's cover needed to be as ironclad as possible. When Snape killed Dumbledore, the entire Order couldn't just pretend to be a little put out. They had to sell it, and that meant that as few people as possible would know.
She noticed how Harry acted more like Voldemort when the locker was on, while Ron had acted insecure and her emotional. She knew that something was off and at that point it was in her head that he was a horcrux.
So why wasn't the Horcrux residing in Harry's head destroyed when he was bitten by the Basilisk? The answer is simple: He didn't actually die. Fawkes quickly healed the bite wound with his phoenix tears just in time. Case closed.
Voldemort wasn't aware of Harry being a pseudo-horcrux because he didn't plan it, and Harry didn't know either until Voldemort “killed” him, but he actually killed the piece of soul kept in him.
Image via Warner Bros. Similarly to Harry, Snape's patronus represents a person. In the memories he gives Harry before his death, Snape shows Dumbledore his patronus, using the form to prove his love of Lily Potter, Harry's mother.
Snape's fierce devotion to and love of his childhood friend Lily, Harry's mother, is the foundation of that loyalty. After Harry Potter and the Half-Blood Prince, Snape's loyalty was a matter of intense debate among the fans.
“Dumbledore didn't want to lose his wand at that point and Draco disarmed him. So that meant that the wand gave Draco its allegiance, even though Draco never knew it, even though Draco never touched it. “From that moment on, that wand gave its allegiance to Draco, and it wouldn't work as well for anyone but Draco.”
Dumbledore knew it meant Harry would need to die in order for Voldemort to truly die, so he was pleased to know that Voldemort's mistake in taking Harry's blood might just save Harry's life.
Dumbledore reveals how thoroughly he loves Harry. Harry is brave, and Dumbledore is proud as any father would be. More than that, Dumbledore succumbs to a parent's weakness; he cares more about Harry's happiness and wellbeing than the wizarding world he is trying to protect.
Severus Snape wanted to teach D.A.D.A. for years, but Albus Dumbledore denied him the job repeatedly, partly for fear of Snape straying back towards the darkness, and partly to keep him around for longer, given the curse on the position. Snape finally got his wish in Harry's sixth year, taking over D.A.D.A.
Narcissa's greatest moment, however, was when she chose to betray Voldemort in Harry Potter and the Deathly Hallows. Not knowing whether Draco was alive or dead, Narcissa chose to lie to the Dark Lord rather than risk losing her son.
Voldemort intentionally made six Horcruxes, but when he used Avada Kedavra on Harry, he unintentionally created a seventh Horcrux. Instead of dying, Lily's love for Harry created a counter 'curse' known as Sacrificial Protection and saved Harry.
Draco's refusal to reveal Harry's identity to Bellatrix was not because he liked him. It was because he believed that Harry was the only chance they had at defeating Voldemort. At first, Draco admired and revered Voldemort until he threatened his family's safety.