Dude, DH had so many clues that there was more to his relationship with GG, not to mention Elphias Doge's doting over his memory seemed a bit blinded-by-love-my-sweetheart-was-PERFECT. Even if you didn't pick up on it before, looking back at it with that knowledge it is pretty obvious that that's what she intended at the time she was writing it. And how awesome it is that she didn't just shove something awkwardly into the canon because she felt she had to 'represent'. Yes, their relationship WAS a pivotal part of what made Dumbledore who he was, but the books are told from Harry's perspective. Harry has proven himself fucking BLIND when it comes to noticing relationships right under his nose - why in the hell would he have picked up anything on a relationship from decades prior that Dumbledore seemed ashamed of and hurt by anyway? And the most important parts of the relationship, that it WAS vitally important to him, did come across, so the story didn't really suffer or lessen because of its absence.
Okay, there are a million things I could say about this, but there's my two cents. [gets down off soapbox]
ETA: http://callmecaito.livejournal.com/87357.html Hee hee!