Research on mental health following disasters has led to the identification of many individual protective and risk factors for postdisaster mental health. However, there is little understanding of the exact influence that disasters have on the functioning of intimate relationships. Especially relevant are attachment styles, which are likely to play an important role in the provision and perception of social support between partners, and subsequent mental health outcomes. Heterosexual couples (N = 127) affected by the 2009 Victorian “Black Saturday” Bushfires in southeastern Australia were surveyed for disaster experiences, posttraumatic stress disorder (PTSD) symptoms, depression, and attachment style between May 2012 and January 2013, approximately 3 years after the disaster. Using actor–partner interdependence models (APIM), we examined both intrapersonal and interpersonal associations of attachment anxiety and avoidance with depression and PTSD, in combination with shared disaster exposure. Male partners’ attachment avoidance was associated with depression and PTSD in both partners. By contrast, a female partner’s attachment avoidance was associated with greater depression and PTSD in herself, but fewer PTSD symptoms in a male partner. Amid the chronic stressors of a postdisaster setting, the attachment avoidance of the male partner may play a particularly negative role, with his tendency toward isolation and denial becoming especially maladaptive for the couple as a whole. The female partner’s attachment avoidance is likewise an important factor, but its associations with negative social support and relationship breakup must be clarified to understand its impact on partnership functioning.