When Michelle is lying in bed with Ronald sitting next to her and asking what happened, she asks him to leave and turns on her right side in a close-up shot. In the next room-wide shot, she has suddenly returned to her back, and after he has left the next close-up shows her on her side again.
After Leonard drops his suitcase out the window, it isn't there when he goes downstairs to meet up with Michelle.
Although there is a mention of bipolar disorder, Leonard's presentation seems to align with borderline personality disorder more.