Disappointment comes knocking on our door without a notice. It is birthed by the expectations we create.
All of us have been disappointed before at something or someone. It could have well been at ourselves sometimes. Be careful not to let this disappointment translate into disappointment in God.
Proverbs 19:21 reads 'Many are the plans in a person's heart, but it is the Lord's purpose that prevails.'
There are two possible scenarios in why we become disappointed. One, our own choices led to the outcome which didn't measure up to the expectations we set. Two, the Lord's plan has a completely different route than you thought and may take longer than you thought. The latter is actually more often true than we'd like. But God knows the best plan for us. Even if the plan includes more pain and obstacles we desire, God knows it is the path to give you more than you imagined you could receive.
Scripture writes He will never fail you nor forsake you. He is faithful. He does what he says he would do in his timing because He is who he says he is.
Set your expectations on Jesus, not your own efforts. We cannot do anything without him. Everything we've ever accomplished, we did so because of his love for us. How wonderful is it?