Blaming one’s partner is common in couple therapy and such moral comment often evokes affective arousal. How people attune to each other as whole embodied beings is a current focus of interest in psychotherapy research. This study contributes to the literature by looking at attunement during critical moments in therapy interaction. Responses to blaming in verbal dialogue and at the level of the autonomic nervous system (ANS) were investigated in two couple therapy cases with a client couple and two therapists. Video-recorded couple therapy sessions were analyzed using discursive psychology and a narrative approach. The use of positioning, a discourse analytic tool, was also studied. ANS responses of the participants, including the therapists, were measured as electrodermal activity. The findings demonstrate how identity blaming, i.e. positioning the other person in ways counter to their preferred identity narrative, was accompanied by increased electrodermal activity in most participants. In the two cases studied, blaming centered on the themes of loyalty, trust and parenting. It is argued that identity blaming in these thematic domains increases the arousal level of the partners, since disloyalty, unfaithfulness and irresponsible parenting threaten the stability of the relationship.