Chen Gang's feelings for Jiujiu were fondness and adoration, but what was missing was romantic love. It wasn't until much later that he understood this. However, at this point, he believed that loving Jiujiu meant letting her be happy. Since Jiujiu liked Li Duo, all he could do was quietly step aside and protect her from a distance.
Chen Gang noticed Jiujiu's changes early on, noticing her frequent bouts of silent daydreaming. During his summer break after his first year of college, he unintentionally saw Li Duo's name on her study materials. It was everywhere, written in neat handwriting. Some of the words even had water stains on them, their strokes smeared as if teardrops had fallen on them.
Chen Gang felt a dull ache in his heart as he understood why Jiujiu had suddenly become silent. However, he couldn't understand why she would shed tears.