After Neji's death Naruto went with Hinata to fight.They were holding hands and Sakura saw it.She suddenly felt a pain in her chest.And suddenly things became clear.She actually loved Naruto for all of this years but she didn't realized.And now she saw Naruto and Hinata together.Sakura hid her tears.
Sakura: Naruto loves Hinata now.. huh..I..love him so much.Why!?
She went back to the bettlefield because there was nothing she can do about them.Sakura thaught that he really loves Hinata.She wanted to erase all sadness and begin to fight,she put her life on the line now..she actually wanted to get killed because she couldn't stand a pain.