Why does Chunfei deteriorate?

In The Story of Yan Xi Palace, Chunfei went bad, because she learned from her conversation with Fu Heng that her love was a joke.

As early as the name of the pure princess was "Su Jing", the relationship between the two families was good. They met when they were young. At that time, Hao had always had a deep affection for Fu Heng, and he loved him to the bone. However, Fu Heng didn't mean it at all. In the draft, the emperor took a fancy to Sue's beauty and entered the palace. When she left, Sue wrote an affectionate letter to Fu Heng, telling Fu Heng her feelings for so many years, but the letter did not reach Fu Heng.

After entering the palace and becoming a pure princess, she learned from the maid-in-waiting that the letter did not reach Fu Heng, so she always thought that Fu Cha and Fu Heng liked herself for ten years. I found that what I had done before was stupid and naive, so I began to change my temperament and wanted to get back at these two people. I didn't have that kind of respect for the queen as a "sister" before.

Because the queen was pregnant, she gave birth to the seventh son of the emperor, who loved her very much. Yong Cong fell out of favor, and the pure imperial concubine was filled with indignation. At the suggestion of Xian Guifei, Yong Cong died of arson, and the queen committed suicide by jumping off a building, and insulted the queen's maid-in-waiting, Mingyu. Pure imperial concubine deliberately led the emperor to see the scene of Wei meeting with Fu Heng, helped Wei put in a good word, cleared the suspicion and spread rumors. In order to please the empress dowager, she was ordered to hold a palace fair in the palace. Wei made Chunfei lose face with a plan, and all the palaces lost sight of it. Chungui lost face and reputation.