JK Rowling announced in 2007 to an audience at Carnegie Hall that Albus Dumbledore was in fact, gay and always had been...
Q: Did Dumbledore, who believed in the prevailing power of love, ever fall in love himself?
JKR: My truthful answer to you... I always thought of Dumbledore as gay. [ovation.] ... Dumbledore fell in love with Grindelwald, and that that added to his horror when Grindelwald showed himself to be what he was. To an extent, do we say it excused Dumbledore a little more because falling in love can blind us to an extent? But, he met someone as brilliant as he was, and rather like Bellatrix he was very drawn to this brilliant person, and horribly, terribly let down by him. Yeah, that's how I always saw Dumbledore. In fact, recently I was in a script read through for the sixth film, and they had Dumbledore saying a line to Harry early in the script saying I knew a girl once, whose hair... [laughter]. I had to write a little note in the margin and slide it along to the scriptwriter, "Dumbledore's gay!" [laughter] "If I'd known it would make you so happy, I would have announced it years ago!"
Was there ever any textual evidence in the Harry Potter novels that would have led a reader, especially the target readers, to believe this was the case?