Han Yan could see that Yan Yuchu had struck down Yue Zhenglin and the others with the fierceness of a thunderbolt not to entangle her in future troubles. If she was willing, he didn't mind taking the blame for Fourth Miss Zhao's death as well.
But she still decided to act on her own, for one reason only: Mu Cheng's feelings for Fourth Miss Zhao were deeply rooted. Even if she had hurt him to his core, it was possible that some of those feelings lingered deep in his heart. If Fourth Miss Zhao died at the hands of Yan Yuchu, Mu Cheng might end up hating him, and one day seek revenge.
She didn't want Mu Cheng to die by Yan Yuchu's sword. You wouldn't know it from how buoyant and gentle Yan Yuchu seemed in front of her, but he wasn't so kind to others.
If there had to be hatred, let Mu Cheng hate her instead.
However, Han Yan was probably overthinking it.
