Ezekiel 16:59

‘For thus says the Lord Yahweh, “I will even deal with you as you have done, who have despised the oath in the breaking of the covenant.”

Because they have despised the oath they made to God, by breaking the covenant, God will deal with them accordingly. He will initiate the curses of the covenant (Deuteronomy 27:15). Both the marriage covenant and the Sinai covenant are in mind here, the one as a picture, the other as the reality.