In the first two cases, only those who love their wives can do it. In the past, when the purpose of sex was to have children, it was normal for male power to control women's sexual behavior with others in order to maintain blood relationship. Nowadays, with the popularization of family planning policies and means, sex is mostly for physical pleasure, husband and wife adjustment and pleasure. In addition to mutual pleasure, it is also a happy way for couples to have sex with other men as long as they don't have children for each other. Happiness can also be shared. Both husband and wife should remember that they are happy, don't let the other half lose their emptiness, and need to repay each other physically and mentally. This requires both husband and wife to love and trust each other and consolidate marriage and family. This is a breakthrough to break common sense and love.
Third and fourth, the purpose is not pure, which easily leads to the separation and rupture of family emotions.