Patients with functional somatic syndromes (FSS) often display troubled relationships with health care providers, psychotherapists, and significant others. Research shows that patients' history of trauma, attachment disturbances, and mentalization deficits may result in the emergence of maladaptive interpersonal patterns, which may later contribute to the onset and maintenance of FSS, "doctor hopping," and dropout in psychotherapy. As the nature and therapeutic consequences of such maladaptive interpersonal patterns in FSS cannot be understood sufficiently by quantitative methods alone, there is a need for in-depth qualitative research. To address this issue, we conducted a metasynthesis of 23 published case studies of patients with FSS from various psychotherapeutic orientations. Results show that patients with FSS from our sample perceived others as unreliable, that is, unavailable, overcontrolling, and overprotective. To adapt to such unreliable others, patients attempted to please and to control them. Patients also suppressed their emotional awareness and expression. Although alexithymia could also play a role, the primary reason for emotional avoidance seemed to be interpersonal in nature, that is, patients were avoiding negative emotions in order to please and control the unreliable others. The onset and worsening of FSS were associated with both interpersonal and physical triggers. Showing signs of physical or emotional distress led to more rejection, overcontrol, and overprotection from unreliable others, which could create a "vicious circle." Our results suggest that offering a more interpersonal perspective on emotion regulation difficulties would be beneficial for patients with FSS, counselors, psychotherapists, and other health care professionals. (PsycInfo Database Record (c) 2021 APA, all rights reserved).