Disillusion

[Sommer]

Disappointment resulting from the discovery that something is not as good as one believed it to be.

[Marquetta]

The state in which one is not [deluted] by any [false] [comforts].

[Vania]

The psychological event that an individual undergoes when what was once considered to be true (i.e beliefs and ideals) is revealed to be false and [inconsistent] with what is widely agreed upon as truth.
Most common symptoms: disappointment, confusion, [cognitive dissonance], depression, [existential crisis]