She transformed into the short-lived princess in the book and fell into the water at the beginning and lost her memory.
The day Su Nian woke up, Prince Jing Li Xuanji was sitting beside her bed with a deep look in his eyes: "Princess, do you still remember what happened on the wedding day?"
She lowered her eyes: "I don't remember."
He didn't believe it. She didn't believe him either.
The book says that he was ruthless and killed without blinking an eye, and in the end, the entire Su family was executed.
She wants to live. I want the Su family to survive.
So she had to keep an eye on him, guard against him, and when necessary - protect him.