God does not sponsor any ordinary or normal relationship, so every relationship God sponsor are always covenant relationships.
Marriage is a covenant, and for something or for two people to become one, there must be a covenant relationship that should exist between the both of them.
Marriage is a covenant, not a contract, not a event. Marriage will start making sense to you when you begin to view or see marriage as a covenant.
One major reason why marriage should never break, is because of the covenant aspect of marriage, covenant are never meant to be broken.
When you understand that marriage is a covenant and not a contract, you will be careful when making the decision of whom to marry.