Though Sai made her feel horrible I think it was a kinda good thing because she was able to understand how she's been affecting Naruto whom she really cares for with her request which she see's now as selfish and a burden. She wanted him to stop putting himself in harms way and to also break not only him but herself away from Sasuke. It's just that Naruto's bond with Sasuke is much to strong to be broken easily and Naruto is not one to give up. He knows the three of them have a special bond and that Sakura is lying to herself and trying to forget the ties the three of them share as a team/friends/family so he gets angry. I think his bond with Sasuke is stronger than any kind of feelings Naruto can have towards any girl at the moment, though I'm still rooting for a NaruSaku pairing I can see this having an ambiguous ending. I wouldn't mind that either because everybody can say what pairing they prefer and no one can say they're wrong because so and so was made canon.