Why was a novel with many female leads called a stallion and not a breeding pig?

Stallion novels usually referred to novels that involved multiple female protagonists with complex emotional entanglements and conflicts of interest between them. This kind of novel is often called a stallion because it describes the interaction between a group of female characters rather than simply describing the interaction between a group of animals like pigs. Stallion novels often involved complicated interpersonal relationships and power struggles, which often happened between different female protagonists, so they were called stallion novels. The name of this novel came from the theme and plot of the novel, not the number of female protagonists. It should be noted that some novels may be called stallion novels, but there are no complex emotional entanglements and conflicts of interest between multiple female protagonists. This kind of novel might be called a stallion because of the unique relationships and struggles between the characters, not because it included multiple female protagonists.