noun

sadness or displeasure caused by the non-fulfilment of one’s hopes or expectations.

to her disappointment, there was no chance to talk privately with Luke

sadness,regret,dismay,sorrow,dispiritedness,despondency,heavy-heartedness,depression,distress,mortification,chagrin,disenchantment,disillusionment,displeasure,discontent,dissatisfaction,disgruntlement