JKR: I was having a girly chat with Emma in her dressing room about three or four years ago and she said to me “I think I’m gonna end up having to kiss Rupert, aren’t I?” And I said “Well if I write it the way I’m planning to write it, you’ll end up having to kiss both of them.” And she was mortified and rolled off the sofa laughing. EMMA: I was only fourteen! And the idea was absolutely horrific!
This scene was perfect for me except for one thing....the laugh at the end. It ruined it. It seemed like they kept it in because it was what Emma and Rupert would have done, not Ron and Hermoine. Cut that laugh and it was a perfect scene.