That ending though
But like why won't you let that go?
That's just one quality that I don't like in a person (particularly in woman). Sakura's attitude back in the beginning was from liking the cool, above average looking boy, with good hair and cool attitude, while at the same time talking bad to Naruto about his loneliness. When Naruto and Sakura became closer, her feelings for Sasuke were still intact (actually they are still buried deep inside), and soon started doing all she can to help and protect Naruto.
I look at it like this. If I was in Naruto's shoes, then I would not associate myself with a girl that treated me like shit from the very start, and then afterwards she comes around and start cheering me on and being by my side because your dreamboy left the village. If Sasuke stayed in the village I doubt she would still act that way. Just look at her reaction when Sasuke AND Naruto rescued her. She immediately said Sasuke without any mention of Naruto. I don't know about you, but this is why I will never like Sakura.
Now, I know what you are probably thinking. You are thinking that Sakura's hardships and communication with Naruto should make up for her actions in chapter 3, but she is basically choosing Naruto because Sasuke is not around, but as I said if Sasuke was still around in the village then Naruto would have no chance. Even when it came to the plead for Sasuke's retrieval, she was dying in tears because that's how much she cared for him.