Buddha taught about living with disappointment. He said that we experience everything in terms of the Eight Worldly Concerns: gain and loss, praise and blame, pleasure and pain, happiness and unhappiness. We of course want gain, praise, pleasure, and happiness. But the Buddha referred to them as the "terrible twins" because each always arrives with its opposite. One cannot be open to praise and not receive blame. One cannot experience pleasure and not feel pain. This is the nature of the reality that we know.
The Buddha taught that it was the denial of this truth that is the cause of all suffering. You cling to your desire for the positive in life while being filled with aversion to the negative events that occur. Yet despite all your efforts, you don't get many of the things you want, or they don't continue to satisfy you, or they go away. This is the Buddha's first noble truth: the existence of duhkha a feeling of unsatisfactoriness that accompanies every experience in which we are identified with our needs.
Disappointment has a chimerical quality because our minds refuse to accept what is; therefore, we relive the disappointment over and over again, never noticing after the initial experience that it is only a memory we are re-experiencing, much like watching old movie reruns.
Source: Dharma Wisdom