How do childhood sweethearts happen, and why are they so stable?

Question

How can childhood sweethearts exist? and then get happily married 20, 30 years down to road? And stay together till death? What are the ingredients to such powerful love at such a young age? Can any adult relationship rival that?

Answer 1

Childhood sweethearts are raised in the same type of enviroment so they have many of the same wants and desires, and most times their lives are going in the same direction (this is how they tend to meet up 20 or 30 years down the road)

Answer 2

True innocence!