Because Zhang () mistakenly thought that his mother had an affair with Lian Zhiming (), because Zhang never came back after seeing his mother picked up by a man when he was a child (in fact, her mother died of drug abuse), because Zhang's mother didn't let Lian Zhiming tell Zhang about his drug abuse, so there was a misunderstanding, and even Zhiming kept it a secret, so he never said it, but he didn't say it later.