What are the main ways of divorce between husband and wife in feudal times according to the law?

Throughout the feudal laws of past dynasties, there are four ways of divorce: 1, becoming a wife, also known as divorcing a wife. This is the most common way of divorce in ancient China. The so-called "seven out, three don't go"; 2. Harmony and separation. This is an ancient legal system that allows couples to divorce by agreement. From the Tang law; 3. righteousness. This is a compulsory divorce system peculiar to feudal society in China. If an event stipulated by law occurs between husband and wife, between one relative and the other relative, or between relatives of both parties, after the lawsuit is over, it is considered absolutely necessary for the husband and wife to be righteous, and both parties must divorce. From the Tang law; 4. Apply for divorce for specific reasons. For example, the reason for the man's complaint is "the wife ran away" and "the wife killed the concubine". , from Dayuantong system.