Funny you should mention celebrities. Do you realize that it is always the girl that is in love with the celebrity. Think about it, guys don't go to a movie just to see a girl. We usually say, "oh she's hott" then leave the subject. But the girl will fall in love because he's handsome or she likes his character/the way he treats other people, kindness etc. just like Ginny has done with Harry. But as Ginny has done just like any other girl, they either get over that person so they can move on with their life or find someone else to dream over.
(if i'm wrong ladies, sorry this was just my opinion on the subject)
I just read the fist book in which Ginny appeared in, I am really starting to like her character and I'm thinking that she might just have a huge role to play seeing that she's been controlled by voldemort. So maybe Harry and her will be spending more time together!