When we talk about shame we think about what makes us desire not to be there. It is a social and cultural standard that depends only on the subjective: on what others consider regarding the situation, culture or person.
To be ashamed is different from being guilty. To feel guilty has to do with a particular aspect of our action, but to be ashamed involves our whole person. When we are ashamed we want to hide, to be out of sight, or even to be dead. It is far more terrible than to be guilty.
Making someone feel ashamed is to judge the person by what we think should be. It is to be judged by what others think and not by the action itself. So we act by ethics of shame and not by what is good or bad.
The reason to be ashmed is because of what we fear, and that is merely subjective. According to what we value, we judge as good or bad, and that is what harms us, to differ on values.