He couldn't resort to economic sanctions to force Yen Wenqing into error, nor could he use extreme measures against his own son, which nearly drove him mad.
Later, Duan Ruanruan gave birth to Duan Yanbing.
Originally, he did not care for his grandson, Duan Yanbing.
He didn't need a grandson born to a common girl.
What he needed was a descendant of a distinguished family.
To separate Yen Wenqing from Duan Ruanruan, he had his nephew rape Duan Ruanruan, allowing Yen Wenqing to catch them in the act, falsely accusing Duan Ruanruan of having a prior affair with Yen Wenqing's cousin, alleging that Duan Yanbing was born to Duan Ruanruan and Yen Wenqing's cousin.
When conducting the paternity test, he manipulated the results, deceiving Yen Wenqing, and eventually, Yen Wenqing received paternity results confirming Duan Yanbing was indeed born to Duan Ruanruan and Yen Wenqing's cousin.
Yen Wenqing almost went insane and nearly strangled Duan Ruanruan to death.
