And, um, would actually have had page time in the books.
Non writers don’t understand that the main character is not always the one most like you or the one you’d secretly like to hook up with. I don’t think Rowling could “fall in love” with Harry, not enough to insert Ginny as her stand in. I think she sees Harry like her child, and every mother wants to see her son married off happily to someone who can make them happy.