1 Corinthians 7:11-13

But if she does leave him, let her remain single or else be reconciled to him. And the husband must not leave his wife. Now, I will speak to the rest of you, though I do not have a direct command from the Lord. If a fellow believer has a wife who is not a believer and she is willing to continue living with him, he must not leave her. And if a believing woman has a husband who is not a believer and he is willing to continue living with her, she must not leave him.