Government "Marriage" started in 1753 in England and Wales and it was named the Marriage Act of 1753 or Lord Hardwicke's Marriage Act and it called for the couple to be at least 21 years old and if they weren't then they needed the consent of the parent.
Before this law the couple could be as young as seven years old and get married.
They also had to get married in a church or the marriage wouldn't be legal.
The original Marriage Act was the result of the many orphans being abandoned and becoming a burden on society.
The Marriage contract made men responsible for their children relieving society from the financial burden of raising those children and placing it where it belonged.