The story's end is sigh-inducing yet inevitably futile. However, despite having a narrator, it is not divine, incapable of doing everything. If it were, there wouldn't be so much suffering in this world.
By the time he returned home, it was already two-thirty in the morning. He cautiously opened the door, avoiding disturbing Shen Yi upstairs and instead took a drink from the fridge, sitting alone at the balcony table, sipping quietly.
Guilty? A bit!
It sounds laughable. This matter originally had nothing to do with him. Jiang Yu to him was just a stranger he had met once, yet regarding her death, Su Qing did indeed harbor some guilt.
The probable reason is because he has a narrator's insight, knowing things unknown to others, perhaps even capable of remedying some situations, but he didn't achieve it.
