Sakura squeals about how wonderful "Sasuke-kun" is. She knows his favorite food (tomatoes), his favorite color (black) and everything that she could possibly know. Her parents and friends treated her obsession with Sasuke with pity in their eyes. Everyone knows that Sasuke cares little about Sakura and is constantly annoyed by her.
Nothing really changes even as the years pass; Sakura still puts Sasuke above everything, until Sasuke leaves to soon become a missing-nin and Sakura begs for him to take her with him. Even with her tear stricken face, he leaves to exact the revenge he longed for so long. Sakura knows that this is what he is going to do, but a love that borders obsession can do that to a young girl.
Growing up meant letting go of Sasuke, but Sakura can't do it. He is a criminal and killed so many people, she thinks to herself, yet she still can't let him go. Meeting him on the battlefield and watching him trying to kill his former teammates made something in Sakura snap. She was going to fight her former crush with all her might. With a poisoned katana, Sakura fought and didn't win. Both of them fighting to the death and Sasuke expecting to win easily against, as he remembered Sakura the weak link of the team, surprisingly neither dies and it ends as a draw.
He returns with a better mindset and is forgiven for his sins. His brother had done everything to make him stronger, but he had abandoned his friends to kill Itachi. Five years is a long time to be in love, in love with someone who abandoned you and all of his friends, someone who killed so many, thinks Sakura. Yet even as Sasuke starts dating others, he is still her first priority; she heals him when he doesn't want to go to hospital and doesn't reveal his whereabouts when he leaves inexplicably. Even as all her friends start to fall in love, she still pines for Sasuke, the one who she can never have.