It's not 100% sure that Harry will end up with Ginny. Remember that Ginny liked Harry for BEING THE HERO in the first books and I think that's still the main reason that she likes him. I think Harry's hormones took over and even if it was canon it was badly written. Why did Harry like Ginny? That was never mentioned in the book. I hope this relationship will just be a teenage relationship and nothing more. JKR says that Harry and Ginny deserved each other in THIS BOOK. That doesn't mean that Ginny is Harry's lifelong partner (I seriously don't want that to happen). JKR even wrote positively about Cho in book 4 and many people went around cheering for Harry/Cho hoping for a relationship! Maybe that's what they are doing for Harry/Ginny now? Hoping it will last forever! Harry marries his first girlfriend from he was 16 (she was only 15). I've come across many badly written fanfics about Mrs. Cho Potter before everybody started regarding Cho as a crybaby (as I do!). What if Harry falls in love with another girl in book 7? or maybe he finds out that Ginny has given him love potion, with help from Hermione? (their "love" was so fake-ish and badly written that it looked like a result of Amortentia, but I'm not sure....). What if Harry realises that Ginny only likes him because he is the famous Harry Potter and the chosen one? Please J.K Rowling. Don't make the billiant Harry Potter books into bad fanfiction or romantic novels.