The data analysis was based on 41 patient-relative dyads (patients: 39% women, mean age 53.5; relatives: 66% women, mean age 52.16). A significant actor effect from self-efficacy to distress was found for patients (r = -0.47) but not for relatives (r = -0.15). Partner effects from self-efficacy to distress were not significant (r = -0.03, r = -0.001). The actor effect from self-efficacy to anxiety for patients (r = -0.61) as well as relatives was significant (r = -0.62), whereas the partner effect was significant for patients (r = 0.16) but not for relatives (r = -0.46). The results suggest that patients' and relatives' self-efficacy is associated with their distress and anxiety. Partner effects were visible for patients' self-efficacy and relatives' anxiety. These findings suggest that self-efficacy is an important factor for the psychological well-being of patients and relatives and that it may additionally be associated with the partners' well-being. Longitudinal research with larger samples is needed to support the findings.