Some interesting studies about patterns of cooperation and conflict were published in the 1980's. Games were developed to determine the best ways to respond in relationships where you are unsure of how a partner will react. Cooperative and selfish moves were tracked over several rounds to determine consequences for relationships. As soon as player B has begun to play cooperatively, player A follows, by switching to cooperative strategy.
Cooperation pays high dividends.
Relationships where both players played cooperatively, consistently obtained the best results. In a family situation this would be similar to a person beginning in a spirit of cooperation and continuing that way till the other person acts selfishly. Even though a player scored points at the expense of a partner in one round, when someone acted selfishly, selfish moves over time resulted in lower scores. Return to cooperation as soon as there is evidence from the other of cooperation. If a player continued cooperation until the partner twice moved selfishly, scores were even better than if they changed to competitiveness immediately after competitiveness in the partner.