In my work with couples for over thirty years, the balance ratio of fusion and differentiation is an important indicator of couple health. Let’s clarify these concepts beginning with fusion. The classic photo of two Americans traveling in similar Hawaiian shirts in Europe engenders the flavor — two matching bookends. Of course, individuals in a couple create resonance together that influences life style choices, plans, activities, outlooks on life and everyday habits. That resonance, as displayed in a variety of ways, helps the couple align and function with ease. The relationship can hum with the rhythm of basic routines, worked-out choices and habits that allow each individual a level of comfort in the similarity and consistency of their acquired lifestyle and tastes.