Korean:
Devilish Joy (daily reset amnesia)
Find Me in Your Memory (hyperthymesia, memory loss) This is not a romcom but a melodrama.
Healer (PTSD, panic attacks) Not a romcom but an action/thriller. Ji Chang Wook was fantastic.
Hyde, Jekyll, Me (dissociative identity disorder) May be too heavy on comedy for you.
I'm Not a Robot (haphephobia)
Kill Me, Heal Me (dissociative identity disorder, trauma, PTSD)
Still 17 (trauma, coma)
I have a list for Amnesia/Mental Variance/Coma/Brains: https://kisskh.at/list/1XZ625P3