I just finished reading Psalm 89 and it seems like Ethan the Ezrahite directly accuses God of breaking his promise to David. v.39: "You have renounced your covenant with your servant, and have defiled his crown in the dust." Doesn't that directly contradict the nature of God? -- J.A.
You have just read the whole psalm. The writer affirms that God is faithful. Psalm 89 is not accusing God of breaking any promise; on the contrary, God was faithful. It is like 2 Timothy 2:13, one of many N.T. verses emphasizing this same truth.
Have you studied the OT history of Judah? (Specifically, 2 Kings-2 Chronicles and the southern prophets [esp. 7th and 6th C. BC].) Most of the Psalms have an historically discernible context. Without knowledge of this, much of our appreciation of the psalm is severely restricted.
God is faithful.