After the Substitute Gave Up, Mr. Gu Went Crazy

In the book, Ni Li was supposed to be Bai Yueguang's substitute, but she was so obsessed that she actually tried to replace Bai Yueguang. After resurrecting her life, she learned her lesson and vowed to put things on the right track. But, why is the direction getting more and more crooked? [The male protagonist is patient in the early stage and explodes in the later stage]