Massachusetts does not accept common-law marriage in its borders, except by those who have legal common-law marriages elsewhere and move in-state. Even then, the commonwealth has to have a reason and mechanism to recognize the marriage.
Typically, this would be at some crisis, like death, hospitalization or suit for divorce. Then the extra level of government lays on. An appropriate court would have to first rule that the marriage was valid. Only then could the couple or survivor get the settlement, visitation rights or power-of-attorney, or divorce.
An article touching on the complexities, includes, "Suppose you opt for the common law marriage believing that, if the relationship ends, you'll avoid a nasty divorce proceeding. This is a bad reason to have a common law marriage."