The just judgement of God.
Lamentations is five poems written as a result of the judgement of God. Jerusalem faces destruction and the people are killed or exiled.
The writer is not indignant at God that this has taken place. They see to understand this is just; the righteous judgement of the Lord:
The LORD has brought her grief
because of her many sins. 1:5
But as a human it is still hard to see the people face destruction, so there is agony and even bewilderment.
But the triumph of Judah’s enemies has been brought about by the Lord himself.
Just judgment… but as with the God of love and compassion there will be hope.