Because the conversation between Ze and Jing was heard by all four people.
It turns out that my brother is also in this class. The guy next to me is called Leng Binxuan. There is a character named Bin. Could it be Brother Bin? I miss you Bin so much.
——————Snow’s Confessions
It turns out that his name is Ling Yichen. If there is a word for morning, could it be Chen? "I miss him so much. I haven't forgotten Chen. I don't know if Chen has forgotten me."
————————Yi’s Confessions
Why do I see the shadow of Ze on his body? Where are you? I miss you so much.