disappointment: Disappointment is the feeling of dissatisfaction that follows the failure of expectations to manifest. Similar to regret, it differs in that the individual feeling regret focuses primarily on the personal choices that contributed to a poor outcome, while the individual feeling disappointment focuses on the outcome itself (from wikipedia).
Disappointment is a feeling that one will be sure to come across sometime in their lives. Some even might see it too often. However, disappointment strives from one's expectations. Believe in yourself and in others! Turn the disappointment as an encouragement to do more and strive for satisfaction.