As the saying goes, when a man gets a stepmother, he gets a stepfather too. After General Guan married his second wife, the eldest Miss Guan was sent to a temple because her birth chart was supposedly too powerful. At home, her stepmother and younger half-sister bullied and beat her, and even tried to steal her betrothal to the crown prince.
Then Guan Nian, a modern-day psycho, was reborn. Her blade was sharp, and she was ready to kill.
She planned to teach these ancient people what it meant to stop being so damn civil.
Guan Nian pointed the knife in her hand at her fiance and declared, perfectly reasonably, "Assassinating the crown prince is a crime punishable by the execution of nine generations of your family. If even one generation gets spared, you're no man."
The crown prince, unwillingly caught in the crossfire: ...This is completely absurd.
Theme: Make your own way to success
It's written as if the marriage contract is entirely decided by the man and woman. That's not to say it's impossible, but it does not fit the feel of ancient literature.