Intense negative emotions and maladaptive behavioral strategies to reduce emotional distress occur not only in patients with various forms of psychopathology but also in their committed partners. One common strategy to reduce distress is for partners to accommodate to the symptoms of the disorder, which reduces distress short term but maintains symptoms long term. Accommodation is believed to be motivated by the partner reacting behaviorally to the patient's emotions, but the emotions of the partner in this context have yet to be examined. This pilot study examined how partner accommodation related to specific patterns of emotional coregulation between patients with binge eating disorder (BED) and their partners, before and after a couple-based intervention for BED. Vocally encoded emotional arousal was measured during couples' (n = 11) conversations about BED. As predicted, partners' emotional reactivity to patients' emotional arousal was associated with high accommodation before treatment. Thus, partners may use accommodation as a strategy to reduce both the patients' and their own distress. After treatment, partners' arousal was no longer associated with the patients' emotional arousal; instead, partners showed greater emotional stability over time, specifically when accommodation was low. Additionally, patients were less emotionally aroused after treatment. Therefore, treatment may have decreased overall emotionality of patients and altered the association between accommodation and partners' emotional reactivity. If replicated, this understanding of the emotional context associated with accommodation in BED can inform couple-based treatment by targeting specific emotional precipitants of behaviors that maintain symptoms.