People constantly do things to us that disregard the common sense of how people should behave around people they claim to care about.

We expect people close to us to show us kindness. Yet, humans frequently have feelings that are so intolerable and complex that they develop urges to pass them on to others. Put otherwise, humans can end up behaving cruelly to soothe their own sufferings by making someone near them suffer in their stead.

Cruelty is an attempt to make ourselves feel better by doing to someone else a version of what was done to us.

A mother might hint to her daughter, "Don't ever succeed in your life as it would make me feel bad about myself."

Or a father would subtly communicate to his son, "I want you to fail in your career to make me feel better about my own disappointment."

Or a spouse would inject their partner with poison that carries the meaning, "I will repeatedly but subtly disrespect your intelligence to reduce the feelings of rage and powerlessness I experienced as a child."