Youth and Old Men

I think we need to bear in mind that Dumbledore is not just regular old--he is 114/115.  He is old-old, and his life is over 99% complete (though, of course, no one technically knows that yet, in this scene).  So when he says old men are guilty for forgetting what it's like to be young, he is being a little hard on himself.  He is literally 99 years older than Harry.  He was Harry's age 99 years ago.

That being said, I think he is thinking not only of Harry but also Sirius, who is only 36 when he dies.  Dumbledore watched Sirius grow up, and he is already 90 when Sirius starts at Hogwarts.  Anyone who has watched a younger person grow up can understand that youth is a very relative term.  (Just for added reference, Dumbledore was about 54 years older than Minerva McGonagall, who is approximately 61 when Sirius dies.)  Dumbledore regrets not only that he did not consider the depth of Harry's frustration and sense of helplessness at being kept out of the loop, but also that he did not fully appreciate Sirius' burning desire to get out of his family's house and do something impactful.  In his 114 years, Dumbledore has grown wise enough to weigh feelings like those with the risks inherent in acting upon them.  Harry and Sirius have both experienced just enough trauma to want to take action, regardless of the risks.  Dumbledore has a sense of the bigger picture that, regrettably, cannot simply be imparted during a meaningful discussion.  Harry and Sirius were both reckless that night.  Their courage is to be admired, but their methods were desperate, and the consequences severe.  For this reason, Dumbledore seems to wish he had addressed Harry's and Sirius' frustrations, possibly preventing one or both of their desperate acts.

An argument could be made that this is all a bit manipulative--that Dumbledore is telling Harry he is guilty for some vague and forgivable transgression that is adjacent to the actual, more serious issue.  It is understandable that Dumbledore would have trouble remembering what it's like to be 15, and even 36, but that does not mean he should have avoided eye contact with Harry for a year and confined Sirius to a new prison with only menial tasks to occupy him.  But I think Dumbledore is sincere in his expression of remorse, and he believes the two issues go hand in hand.  It all goes to show that apologies are better when the apologizing person fully understands their transgressions.

--AK