Wikipedia
Enoch Arden law
The Enoch Arden law is a legal precedent in the United States that grants a divorce or a legal exemption so that a person can remarry, if his or her spouse has been absent without explanation for a certain number of years, typically seven.
After seven years the missing spouse can be declared legally dead.
The "Enoch Arden doctrine" is named after Tennyson's melodrama Enoch Arden.