"Ephraim, what shall I do to you? Judah, what shall I do to you? For your love is like a morning cloud, And like the dew that disappears early.
Note the mention of both Ephraim and Judah in this verse.  Despite the rebellious division of God's people under Jeroboam I, the prophets, in their messages to either Judah or Ephraim never leave the whole people of Israel very far out of sight.  It is not kingdoms, per se, that God addresses, but the whole covenant people.  It is blindness to this fundamental truth that results in foolish and unprovable opinions to the effect that certain passages mentioning Judah are interpolations.