The other commenters are demanding 12-year-olds to be unrealistically sane.

But 12 year olds are sane - at least relative to what will be going on three years hence. If I were to criticize EY's handling of this stuff, it is that he should have followed canon by putting off dealing with romance issues until the kids are in their third or fourth Hogwarts year.

But, if EY has to drag romance into this story, I wish he wouldn't have the heads all of his minor female characters so filled with romantic mush and gossip about same that they don't seem to be much use for any other purpose. Eliezer gives his male characters a variety of idiosyncratic, yet typical young male foibles - twin Weasley pranks, Ron Weasley quiddich mania, Harry's enthusiasm for things military, even Draco's misogyny. I wouldn't mind if he teased his female characters regarding a variety of equally silly and endearing stereotypically female traits. But it seems he can only think of one.