An existential crisis (PROSE: The Avant Guardian, Lonely) also called existential angst (PROSE: Jealous, Possessive) or existential despair, (PROSE: Snowman in Manhattan) was related to the questioning of one's own life or existence (PROSE: The Slow Empire) and a feeling of loneliness. (PROSE: Lonely)
The idea that a robot personality matrix really believed itself to be the Seventh Doctor made Forgwyn "go existential all over". (PROSE: Tragedy Day)
The Eighth Doctor recognised that Jamon de la Rocas was going through a "somewhat rocky existential time of late", "worrying about the existence of self, souls, prana and whatnot". (PROSE: The Slow Empire)
Every year, Alan Wood felt existential despair at the prospect of another relentlessly commercial "holiday season". (PROSE: Snowman in Manhattan)
Faceless43 joked that the "party" at #areyoulonely was "BYOEC", or "Bring Your Own Existential Crisis". (PROSE: Lonely)