Example:
Yong Zhengdi and Lv Siniang.
Yongzheng's "literary inquisition" killed the Lv Siniang family, and Lv Siniang once assassinated Yongzheng in the palace.
Qin Shihuang and Evonne
Because Zhao Ji had an affair with Lao Ai, Qin Shihuang held a grudge and eventually put Evonne to death.