'But the patient doesn't seem borderline': some observations on a common diagnostic error.

Borderline personality disorder (BPD) may be overlooked when the therapist does not occupy the role of primary attachment object. In such cases, characteristic borderline dynamics emerge chiefly in external relationships rather than within psychotherapy, leading clinicians to underestimate the disorder. Drawing on Gunderson's original ego psychology-object relations model, this paper argues that BPD is fundamentally organised around relationships with emotionally significant others. Diagnostic formulations that rely heavily on transference dynamics may therefore miss BPD in seemingly organised patients whose central conflicts are enacted outside treatment. Gunderson's model thus remains essential for understanding the interpersonal core of borderline psychopathology.