Without Ning Yu, Liu Jing would not be emperor.
So Liu Jing was always a little afraid of Ning Yu, so scared that she wanted to kill her.
Without Liu Jing, Ning Yu would not be the queen.
Ning Yu knew that Liu Jing was afraid, so she didn't hide away, and spent the rest of their lives in Ming Palace amidst the infamous reputation.
Liu Jing: I trust Ning Yu calmly, not because I trust her, but because I love her. Although I never said it to her personally.
Ning Yu: He said that in a dream.
Purpose: About growth and reconciliation