A childhood belief about marriage

When I was little, I used to believe that divorce was mandatory, and you were only allowed to be married for a specific period of time. I don't know what I thought happened afterwards, but I remember being in my mother's car in the driveway at the age of 4, listening to a song about everlasting love, and then saying "Yeah, until you get divorced." My mother thought I was being needlessly cynical, but I really thought that was what happened, and that someday in the distant future, my parents would get divorced.