Common law is just like marriage, but without "the piece of paper".
Living common law before marriage dramatically increases the changes of divorce and decreases the happiness within that marriage, than if they had just got married to begin with.
Couples who live together before marriage to see how well suited they are for one another, have more satisfying and longer lasting marriages than couples who do not. (Those who never live together have more satisfying and longer lasting marriages than those who live common law.)
Living common law is an effective tool in reducing your risk of divorce if you finally marry that person. (The rate of divorce for those who marry after common law is much higher than virgins who married)
The physical health, wealth, and emotional benefits associated with marriage are the same for common law relationships proving that common law is "marriage without the piece of paper." (The benefits of common law partners are almost the same as those associated with being single. Marriage brings many extra physical health, wealth, and emotional benefits that living common law does not.)
Its better for a single mom to live common law, than alone with her children. (Single parents should never live common law because of the extreme risk of doing permanent damage to the children in so many different ways. 75% of common law relationships with children split up before the child reaches 16 years old. This split up of the common law partners is as damaging to the children as a divorce.)
Women and children are safer from domestic violence and sexual abuse in common law marriages because the woman is free to leave if the man hits her or abuses the children. (Women living common law have much higher domestic violence rates than married women and much higher risk of physical and sexual abuse for children.)