Here's a question: when did she ever compare the two and say, "Sasuke is more for me" or any sort of similarities? The thing is people are often not understanding on their own feelings or even needs. You get movies that have them thinking what's best for themselves, right or wrong, but if there's a bystander and actually suggest the other guy, then maybe he/she would reconsidered. For example:I still have a hard time that Naruto wins her over when there's still evidence that in Part 2 she prefers Sasuke over him.
Sakura: Sasuke-Kun is just dark, I don't know if he's the right guy.
Gaara (example, ok): Well, I don't know much about romance. However, maybe he's not the guy. Perhaps there's another that makes you happy. Naruto sounds like the guy.
Sakura: Naruto?
Gaara: Yes. I mean I have know him for a short time, but he gives me that vibe of a honest guy. You know him more than I do as well as being with him for a long time. Perhaps there's something that you feel like you don't truly understand.
Something like that. She never compare. If she truly still loves Sasuke today, then you have to give her time to let it go. Yes, I know she should have a long time ago, etc. but again, if the moral is there, I guess it has to be done on purpose.