1 Corinthians 7:10-12 New International Version - UK (NIVUK)
10 To the married I give this command (not I, but the Lord): a wife must not separate from her husband. 11 But if she does, she must remain unmarried or else be reconciled to her husband. And a husband must not divorce his wife.
12 To the rest I say this (I, not the Lord): If any brother has a wife who is not a believer and she is willing to live with him, he must not divorce her.