'It is not surprising...that after children leave home, many marriages fall apart. Why? Because while the parents treated their relationship with their children as a covenant relationship - performing the actions of love until their feelings strengthened - they treated their marriages as a consumer relationship and withdrew their actions of love when they weren't having the feelings. As a result, after two decades, their marriages were empty while their love for their children remained strong.'
Timothy Keller with Kathy Keller, The Meaning of Marriage, p.108.