When she chose to stay, she thought she was saving a man in dire straits.
Xu Yan traveled through time and became the contracted wife of Gu Huaijin, the villain in the book. Faced with her "bankrupt" husband, she decided not to leave him and use her wisdom to prop up this crumbling home.
What he didn't know was that her staying was the only variable in his chess game.
Gu Huaijin has already laid a dragnet, and the so-called bankruptcy is just a disguise to fight against the "way of heaven" fate. He thought he was protecting her, but he didn't know that she had already become the brightest light in his dark plan.
A two-way disguise, a game that subverts fate.
They were protecting each other in their own way, and it wasn't until the truth was revealed that they discovered that they were already comrades and lovers whose souls fit together.
When they met at the deepest trough, they thought they were redeeming each other, but they didn't know that there was a world hidden in each other.