You misunderstand.  Way off. 

The goal isn't "procreation"...the goal is total unity and openness to God's will. 

A man and woman (in a married state) seek unity with themselves and with God's will, and are fully "open" to the consequences of that natural act of complementarity. 

Long past fertility, the goal is still the same. 

Think more supernaturally, and it will start to click.