I get why the top (color) panel might be interpreted as sadness, but that's not the way I see it.
When I look at that panel I see introspection. I see Sakura being convicted by the true desire of her heart and not comprehending what it means. I see a deeper version of this:
She has feelings for Naruto that she doesn't have for anyone else. She has an incomparable bond with him that she doesn't know how to label.
The top panel -- when she realizes Hinata's feelings -- is a softer, gentler reflection of Inner Sakura. Inner Sakura is attracted to Naruto and his personality, and really gets him. But that part of her is ruled by her conscious mind that hasn't figured out or accepted the truth yet. The result is conflict and confusion.
I think Kishimoto has done a great job of showing Sakura's journey toward realizing her feelings for Naruto. He's given just enough hints that we can see her love for him taking shape, but has kept the full realization from her and us.
The wait for it is frustrating, but it's going to be so worth it.
I think there will be a certain moment that will spark those feelings. Whether it is something that Naruto does or just a general realization. I want to know how kishi will make her realize her true emotions towards naruto. However, I think someone posted something similar to this where naruto does something clumsy or stupid again which makes sakura worry or understand her emotions, she goes to hit naruto again much like the pain arc but naruto stops her and does something on his own. I would love to see this but the wait is horrible :( .