Since Jeremiah spends so much time warning about God's wrath, the parts that focus on compassion and forgiveness come as a surprise and a relief. Although God acts like he's condemning Judah permanently, he makes it clear that that really isn't the case. He'll forgive them once they've served their time, and he'll lead them back to Judah, where everyone will obey God and live happily ever after (or at least until Roman times). Even the other countries that God threatens with destruction will be restored after their time of punishment has elapsed. So in the grand scheme of things, we're looking at just one phase here. It gets better, but it's probably hard for the people to see that in the face of all the calamity.
Questions About Compassion and Forgiveness
Are there limits to God's mercy in the book of Jeremiah?
Is the God of Jeremiah less compassionate than the God of Isaiah? Of Ezekiel? Compare them (if you've read the Major Prophets).
Is forgiveness really forgiveness if you're punished first?
Does the sharp contrast with God's wrath help to bring out the meaning and importance of God's mercy?