There was no such thing as nonchalance. She cared very much. Too much.
She remembered clearly all the hurtful things Gu Yu had said to her. She was just pretending that she didn't mind. But, at that moment, she finally knew that what she had always been waiting for, was his apology.
Did he finally understand how much he had hurt her? Did he finally know how much pain she suffered because of him? Did he finally realize that he was in the wrong?
That knife was nothing.
The pain from that knife wasn't even a fraction of the pain he caused her!
Did he know how she felt when she stepped on the land of another country? Did he know how she tossed and turned in bed while she was overseas? Did he know the pain she went through during those three years? Did he know what low expectations she had at the start after she married him? Did he know how he doused her flame of hope slowly, bit by bit?
In that instant, she really wanted to scold him.