He felt that it was not safe to be implicated by the curse.
He was afraid that Yu Su's life would be in danger. If hse could undo it, she should do it as soon as possible.
Otherwise, he would always feel uneasy.
Yu Su thought for a moment and also wrote on the notebook, "I'm afraid this incantation can only be completely resolved if the person who cast the incantation undoes it or if the person who cast the incantation dies. Otherwise, both sides might suffer a backlash if it's forcefully removed. Anyway, the luck is with me now. Yu Miao's luck is getting worse and worse, so there's no hurry."
This was the viciousness of the incantation.
Even if she saw through it, there was no way to remove it. If she had removed it forcefully, both sides would be injured, and she might alert the enemy.
The three of them were writing when the doorbell rang again.