Despite research suggesting increased anxiety and depressive symptoms after a perinatal loss and during future pregnancies, little knowledge exists to guide clinicians treating pregnant women after perinatal loss. This case study explores processes that facilitated therapeutic change for a pregnant patient with major depressive disorder (MDD) and posttraumatic stress disorder after perinatal losses. The study integrated quantitative and narrative analyses in a single case derived from the pilot phase of a randomized controlled trial on supportive-expressive therapy for MDD. The quantitative and narrative analyses suggest that an improvement in maladaptive interpersonal patterns toward the therapist, in the form of attachment avoidance, made it possible to form a strong alliance, which in turn led to a successful outcome. The findings highlight the importance of improving maladaptive interpersonal patterns as a prerequisite to enable patients after pregnancy losses to develop and maintain a corrective therapeutic experience.