it’s obvious to me that Sakura is looking at Sasuke this way because she has feelings for him. She has hopes.
Sakura has romantic feelings for Sasuke and she is giving him this look because she is hoping for something more (though, we know how that ends).
It’s a simple use of body language. Glancing can betray a desire for a certain thing. For example glancing at the door can indicate a desire to leave.
That’s when I took a closer at this scene:
I could tell that Sasuke was giving Naruto the same look which Sakura was giving Sasuke. But, there was more meaning in this glance. Sasuke looks sad when he is looking away. It indicates the regret which he feels for pushing Naruto away.
Then, he takes a glance at Naruto (2nd GIF) which is just like the way in which Sakura looked at Sasuke.