["Clinical Psychology &Psychotherapy, Volume 33, Issue 4, July/August 2026. ", "\nABSTRACT\nThis study examined therapists' assessments of post‐traumatic stress disorder (PTSD) symptoms and disturbances in self‐organization (DSO), the additional symptom cluster that distinguishes complex PTSD (CPTSD) from PTSD in ICD‐11. We investigated how these dimensions, together with patient dissociation, shape therapists' affective responses and in‐session disconnection, considering both patient (CADS; observer rated) and therapist (DES; trait) dissociation. Therapists (N = 60) completed measures referring to one selected patient. Measures included PTSD and DSO symptoms, personality organization, self‐concept clarity, adverse childhood experiences, interoceptive awareness, patient dissociation, therapist affective responses, therapist dissociation and therapist in‐session disconnection. Correlational analyses, MANOVA and hierarchical regressions were conducted. DSO and PTSD showed distinct profiles of functioning. DSO was associated with broader structural vulnerabilities, including impaired personality organization, adverse childhood experiences, reduced interoceptive awareness and higher dissociation, whereas PTSD was primarily associated with reduced self‐concept clarity. DSO predicted therapists' feelings of helplessness, whereas patient dissociation predicted overwhelmed/disorganized responses and reduced positive engagement. Patient dissociation and therapist dissociation independently predicted therapists' experiences of in‐session disconnection, while their interaction was not significant. Findings highlight distinct relational correlates of DSO and PTSD and identify dissociation as a central mechanism of therapeutic disconnection. Dissociation operates as a shared field phenomenon, with clinical implications for monitoring and addressing in‐session relational ‘drifts’.\n"]