1 Corinthians 7:10-13

ISV(i) 10 To married people I give this command (not really I, but the Lord): A wife must not leave her husband. 11 But if she does leave him, she must remain unmarried or else be reconciled to her husband. Likewise, a husband must not abandon his wife.
12 I (not the Lord) say to the rest of you: If a brother has a wife who is an unbeliever and she is willing to live with him, he must not abandon her. 13 And if a woman has a husband who is an unbeliever and he is willing to live with her, she must not abandon him.