Why does sister-in-law hate sister-in-law

1, because my sister-in-law is always United with her mother-in-law, she will think that her daughter-in-law will bully her mother. To put it bluntly, it is still a deep-rooted contradiction between mother-in-law and daughter-in-law.

2. Sister-in-law goes back to her parents' home to facilitate communication and speak casually. She doesn't like some of her aunt's behaviors, doesn't listen to what she thinks is offensive, and finds fault with the head of the family.