'Separate' in the Bible

and to the married I announce -- not I, but the Lord -- let not a wife separate from a husband:

but and if she may separate, let her remain unmarried, or to the husband let her be reconciled, and let not a husband send away a wife.

And, if the unbelieving doth separate himself -- let him separate himself: the brother or the sister is not under servitude in such cases, and in peace hath God called us;