The Family Model Model offers both simplicity and complexity in understanding couple dynamics.  FIRO stands for Fundamental Interpersonal Relations Orientation.

Simple because it focuses on couple interactions in just three areas: Inclusion, Control, and Intimacy.  

Complex because it shows how to prioritize which areas to work on first, and which next, and so on. And if that's not enough, the model offers a way to assess problems occurring in the therapeutic system consisting of the spouses and the therapist.  

There is a big payoff for therapists who use this intuitive and easy-to-grasp model. This video gives a comprehensive overview.