The Book-Traveling System Is Abnormal

There is a world behind a novel, and each world has its own administrator who manages the order of the world. Wang Yuan, an ordinary acting graduate, woke up and inexplicably slipped into the novel "Rebirth of the Shadow Queen" and became the vicious female supporting character with the same name in the book. In order to maintain the stability of this world, and to return to his own world as soon as possible, Wang Yuan reached an agreement with the administrator of the book, completed the plot, and then returned home. However, why did the plot still collapse so badly?