Disappointment can emerge when your expectations have not been met. The primary cause of disappointment is setting your heart on people or circumstances. We are to guard our heart above all things (Proverbs 4:23). God is the only one that is deserving of our whole heart.   

“I will love You, O Lord, my strength. The Lord is my rock and my fortress and my deliverer; My God, my strength, in whom I will trust;

My shield and the horn of my salvation, my stronghold. I will call upon the Lord, who is worthy to be praised; So shall I be saved from my enemies.” Psalm 18:1-3