When Jeremiah picks up his indictment of Israel again in Jeremiah 3:20, he uses the term “Israel” to refer to both Judah and the Northern kingdom, Israel, with its capital in Samaria. As His child, Israel had become prodigal. God calls them to come home. As a spouse, Israel 
had been unfaithful and has forsaken her vows. This verse uses a new word for her infidelity. Jeremiah speaks for God, “Surely, as a treacherous wife leaves her husband, so have you been treacherous to me, O house of Israel, declares the LORD.”
Lange observes that, Israel takes “…it as an affront to be told of their faults, and called upon to amend them; … They are so ignorant of themselves, and of the strictness, extent, and spiritual nature of the divine law, that they see nothing in themselves to be repented of; they are pure in their own eyes, and think they need no repentance. Many ruin their souls by baffling the calls to repentance.”[1] But the idols they refuse to abandon bring no satisfaction in the end. The bleed us dry of life, health and contentment and simply drive us to lust for more. There is a true emptiness in the pursuit of the pleasures of the flesh, the pride of life, and the lust of the eyes. There are no lasting joys in serving these idols. It’s the end of these pursuits that brought the prodigal son to his senses. It was so for many others since then as well.
Spurgeon said, “The worst of crimes—that a wife should be false to her marriage vows, and turn aside from her husband whom she is bound to love; and very seldom is it that a husband calls a treacherous wife back again,—but God in infinite mercy hates putting away. He cannot bear divorce. He holds still to the object of his love; and therefore complains with a sweet fidelity of affection, of the treachery of Israel; and while he is doing it a voice is heard upon the high places, weeping and supplications of the children of Israel, for they have perverted their way, and have forgotten Jehovah their God; and therefore what was there for them but sorrow. They were on their high places offering sacrifice and incense to their new gods; and instead of joy and holy psalms and hymns of delight, they were crying like the priests of Baal, and cutting themselves and torturing themselves. God heard it, weeping and supplications, not to him, for they had perverted their way. Their sorrow did not come from him, for they had forgotten the Lord their God. But that sorrow had something hopeful about it. They found no joy in their new gods, and derived no comfort from their backslidings.”[2]
[1] John Peter Lange, Philip Schaff, and Joseph Packard, A Commentary on the Holy Scriptures: Malachi (Bellingham, WA: Logos Bible Software, 2008), 23.
[2] C. H. Spurgeon, The Metropolitan Tabernacle Pulpit Sermons, vol. 58 (London: Passmore & Alabaster, 1912), 504.