The character of Alex Forrest has been discussed by psychiatrists and film experts, and has been used as a film illustration for the condition borderline personality disorder. The character displays the behaviors of impulsivity, emotional lability, frantic efforts to avoid abandonment, frequent severe anger, self-harming, and changing from idealization to devaluation; these traits are consistent with the diagnosis, although generally aggression to the self rather than others is a more common feature in borderline personality disorder. Some have instead considered the character to be a psychopath.
As referenced in Orit Kamirs' Every Breath You Take: Stalking Narratives and the Law, "Glenn Close's character Alex is quite deliberately made to be an erotomaniac. Gelder reports that Glenn Close 'consulted three separate shrinks for an inner profile of her character, who is meant to be suffering from a form of obsessive condition known as de Clérambault's syndrome' (Gelder 1990, 93—94)".
The popular term 'bunny boiler', used often to describe an obsessive, spurned woman derives from the scene where Alex boils the pet rabbit.