The legitimate daughter becomes cannon fodder? Rebirth to overthrow the system's fatality

Beautiful and vicious noblewoman from an aristocratic family & cold and restrained black-bellied young man Cheng Jiuyuan has had a smooth life since birth. Her grandfather is as wealthy as a country, her father holds real power, and her fiance is the crown prince, which is enough for her to run rampant in Kyoto. Until her engagement was taken away and she was forced to marry the enemy country, until the last moment of her life, she realized that all this was calculated by her so-called relatives and lovers. "I'm sorry, sister, I can only complete the task by taking away your fate and saving the second female." "I'm sorry, I can't marry a woman who has been married, not to mention that you are the concubine of the enemy country." Since you say you're sorry to her, then give everything back to her! In her new life, she takes back her fate...