"Harp" means deep affection and strong love. Shengxiao Mo means to leave quietly.
In this novel, He He was separated for seven years because of family and misunderstanding when he was young, but when they met again, they were strangers. This sentence is a true description of their feelings at that time, expressing their helplessness to fate and regret that they can't be together when they love each other.
Unintentional novel "Why Shengxiao Mo"? "I have always been superficial, but I have deep feelings. Since I can play the harp, why Shengxiao Mo? "