(1) Mr. Wang once met a woman named Pan, and they fell in love. Later, for some reason, that woman named Pan left him, which made him unable to let go for a long time. Therefore, in his own works, he wrote all the bad women as women named Pan to pour out his inner anguish. It sounds reasonable, but it's not elegant. (2) The Water Margin was written in the Song Dynasty. At that time, the traitors were in power and there was a Pan Renmei. Everyone knows that Master Pan betrayed the country, colluded with foreign countries and killed the Yang family in Zhongliang. At that time, it was reviled by everyone, and Pan became a surname that everyone didn't like. Therefore, in "Water Margin", two bad women were written, both surnamed Pan.
(3) When Shi Naian was young, he took part in the peasant uprising and joined Zhang Shicheng as an adjutant. Later, I found that Zhang was not enough to achieve great things, so I left Zhang. Zhang Shicheng has a son-in-law named Pan, and this son-in-law has a brother named Pan Yuanming, both of whom are highly valued by Zhang Shicheng. Later, Zhu Yuanzhang led the troops to crusade against Zhang Shicheng, and Pan and his two brothers actually defected to Zhu Yuanzhang, becoming the enemy of Zhang Shicheng and the driving force behind Zhang Shicheng's defeat. Shi Naian heard about it. Although he has left Zhang Shicheng, the victim's feelings are still there, and he especially despises what the Pan Shi brothers did. So in his own pen, he named two unfaithful women Pan.
History is not elegant and can only be guessed. What is the specific reason remains to be carefully researched by future generations.