For an introduction to this series, click here.
It would be nice if Jeremiah ended his lamentations with hope for the future or a promise of good days to come. Unfortunately, there are none, unless you count 3:22-24, which reads:
The steadfast love of the LORD never ceases;
His mercies never come to an end;
They are new every morning;
Great is your faithfulness.
The LORD is my portion, says my soul,
Therefore I will hope in him.
Based on the rest of the passage, I think this is little more than a statement of fact on Jeremiah's part. Yes, he knows that God is faithful, and that He has a plan for all of this, but that doesn't take away the pain of seeing Jerusalem destroyed and seeing God's people suffer.
Pain and suffering are part of life, and to deny the existence of suffering or to offer platitudes about life being good all the time because we are saved is childlike at best and at worst nihilistic. God could have come through with a miraculous solution to all of Israel's and Jeremiah's problems, but He chose not to. He allowed Jeremiah to endure terrible heartache and suffering, all without an explanation. Of course, he was allowed the privilege of writing two books of the Bible, but I bet if you came to Jeremiah as he was penning these verses and offered him a choice of an easy solution or a chance to write Scripture, Jeremiah would have chosen the easy solution. I'm pretty sure I would have, anyway.
But Jeremiah, like Job, accepts God’s wrath and trusts in His ultimate justice:
Who has spoken and it came to pass,
Unless the Lord has commanded it?
Is it not from the mouth of the Most High
That good and bad come?
Why should a living man complain,A man, about the punishment of his sins? (3:37-39, ESV)