The government only steps in when a dispute arises to figure out who was right and who was wrong. Describe how a legislator might analyze a family issue using your approach. In the case of the family, the concern is that all sorts of bad things happen, like spousal abuse, and neglect and abuse of children. One view is that these are problems in which the government should intervene with police, injunctions and other tools of the law. But if the government intervenes too much, the family as an institution may fall apart because it needs autonomy to persist.
Game theory provides a model for social organizations and cooperation between individuals.
It assumes that people are rational actors. Game theory uses a theoretical construct that sets aside affection or altruism or a sense of solidarity as factors in cooperation. In the classic Prisoner's Dilemma of game theory, people will rationally cheat each other and engage in opportunism unless something prevents them from doing so. In game theory, cheating and cooperation are rational choices. If I cheat you today, I won't be able to cooperate with you tomorrow.