control (freak)
one day it dawns on her that perhaps the reason she's so chronically untidy is that it's a control issue - it's her space and she made it that way, etc. rebelling against her super-neat parents' lifestyle/values, obviously.
after further thought she decides that if she could be quite certain nobody would poke through her stuff (or remove books, watch movies, etc), the obsession would be manageable.
fat chance.