The Undoing. It basically already is an upmarket '90s erotic thriller, but the key to those films' success was that they told their story in about 90-100 minutes and got out before you started to really think about the plot and how little sense it made; The Undoing took six hours to reach more or less the same conclusion as Jagged Edge or Primal Fear, and I think people would've been a lot more forgiving of that non-twist ending had it not taken them so damn long to get there.