When the things go against our expectations, disappointment is inevitable. You are so right in saying that disappointment comes from the expectations unmet.

We may also be a reason of someone's disappointment. Sometimes we know that. Sometimes we don't. We should try to avoid hurting others as much as we can but the problem is sometimes people sre themselves prone to get hurt. Nothing can be done in this case.

As you said we should try to get rid of the feeling of disappointment as soon as we can because it is not good for our mental and physical wellbeing. For dealing with disappointment, forgiveness is a tool we can make use of.

!hivebits