Giana opened her eyes when she was sure that Dillon had fallen asleep, because after the sweetest sin they had committed was over, Giana didn't know how to deal with Dillon and chose to pretend to be asleep.
She needed time to think about how she should act or what her next step should be.
Giana was really playing with fire, which was none other than Dillon's feelings. Somehow, she knew that one day she would be burned, but for now, this was the only way she could think of to draw Dillon back to her.
Maybe now Dillon thought that Giana was trying to open her heart to him, even though what Giana felt for Dillon was still the same.
Giana felt so shameful for taking advantage of Dillon's feelings for her. The only man who had never hurt her, but she had to do all of this, because she couldn't think of any other way.
Giana needed Dillon, but not in the way that Dillon wanted her and for that, Giana felt bad for him.