Person B: Damn You, “Evanescence”!!!
evanescence – noun
evanescent – adjective
evanesce – verb
Soon passing out of sight, memory, or existence; quickly fading or disappearing.
oxforddictionaries.com
The term Evanescenceevanescence, as applied to dream psychology, is indeed used in dream psychology (as well representedas in a browser search.some musical pieces):
... the dream's evanescence, the way in which, on awakening, our thoughts thrust it aside ...
Sigmund Freud, Dream Psychology
There are several established theories that help explain the evanescence of dreams.
Huffington Post, “Why Do We Have Trouble Remembering Our Dreams?”