Disappointment is the feeling of dissatisfaction that follows the failure of expectations or hopes to manifest. Similar to regret, it differs in that a person feeling regret focuses primarily on the personal choices that contributed to a poor outcome, while a person feeling disappointment focuses on the outcome itself.
This ranks right up there with lying and deceit.....although they seem to all be entwined. Definitely a feeling that's hard to forgive!
Proverbs 16:9 (ESV) 9 The heart of man plans his way, but the Lord establishes his steps.