I often speak about the importance of an anual vision quest for couples. A time when a couple take the time to check that their relationship is still 100% on track.
The vision quest is an important focal point for the relationship because it steps away from the emotional seesaw that can become the "who's treating who better or worse" debate that couples often use to determine the health of their relationships. It doesn't work like that.
In all of nature, things have purpose. Everything merges with something to create, and humans are no different. IF we no longer have a common purpose, - at least 33.3333% overlap in objectives and outcomes, the relationship will gravitate to self obsession and huge emotional instability.
The following article sheds further light on that subject The Science of Prayer - http://www.psychologicalscience.org/onlyhuman/2010/01/science-of-prayer.cfm