44 Lastly, since We well know that none should be excluded from Our charity, We commend, venerable brothers, to your fidelity and piety those unhappy persons who, carried away by the heat of passion, and being utterly indifferent to their salvation, live wickedly together without the bond of lawful marriage. Let your utmost care be exercised in bringing such persons back to their duty; and, both by your own efforts and by those of good men who will consent to help you, strive by every means that they may see how wrongly they have acted; that they may do penance; and that they may be induced to enter into a lawful marriage according to the Catholic rite.
Source: Arcanum Divinae (Vatican.va)