Purpose Of The Relationship: It's a very simple program. Read 1st Corinthians 13.

The truth is that the purpose of the relationship is the companionship of the couple.  This remains the most important priority even after the couple becomes mother and father to a child since children do not want to be raised in an unhappy home environment where the couple has lost sight of the most important denominator in their relationship although they are now parents.   That is companionship.  See Elizabeth and Zacharias.  Companionship of the couple comes first and remains as the first priority for the blessed happiness of the home.