M.G.L. c. 208, § 2

Causes for divorce; confinement for crime

A divorce may also be adjudged if either party has been sentenced to confinement for life or for five years or more in a federal penal institution or in a penal or reformatory institution in this or any other state; and, after a divorce for such cause, no pardon granted to the party so sentenced shall restore such party to his or her conjugal rights.