Psalm89 - trust near a denial of reality

In the old testament, we read promises to David: his kingdom will last forever. The psalmist is very aware of this promise to David:

3 You said, “I have made a promise to my chosen one.

    I swore this oath to my servant David:

4         ‘I will make your dynasty continue forever.

        I built your throne to last throughout every generation.’” Selah

He remember this promise again:

35 On my holiness I have taken an oath once and for all:

    I will not lie to David.

36 His dynasty will last forever.

    His throne will be in my presence like the sun.

37 Like the moon his throne will stand firm forever.

    It will be like a faithful witness in heaven.”

However, there is no descendant of David ruling  during the exile in Babylon. We Christians understand that "Jesus is the solution", through Jesus, a descendant of David reigns forever.

I don't know when Psalm 89 was written, but it seems to me that it reflects questions in Babylon exile in verses:

38 But you have despised, rejected,

    and become angry with your anointed one.

39 You have refused to recognize the promise to your servant

    and have thrown his crown into the dirt.

40 You have broken through all his walls

    and have laid his fortified cities in ruins.

41 (Everyone who passed by robbed him.

    He has become the object of his neighbors’ scorn.)

42 You held the right hand of his enemies high

    and made all of his adversaries rejoice.

43 You even took his sword out of his hand

    and failed to support him in battle.

44 You put an end to his splendor

    and hurled his throne to the ground.

45 You cut short the days of his youth

    and covered him with shame. Selah

46 How long, O Yahweh? Will you hide yourself forever?

    How long will your anger continue to burn like fire?

The psalmist is very upset. Given what is happening, it seems that the promises were a lie (opposing to verse 35). Despite all circumstances, the psalmist decides to trust in the Lord. That is why he is questioning the Lord, because he trusts in Him. He finishes the Psalm with:

51 Your enemies insulted me.

    They insulted your Mashiach every step he took.

52 Thank Yahweh forever.

    Amen and amen!

We Christians trust in the Lord. We know that his promise to David was fulfilled in Jesus. However, this psalm inspires me to trust in the Lord near a denial of reality.