Complicated grief has many interfaces with post-traumatic stress disorder (PTSD) including avoidance, flashbacks and shattered assumptions. Increasing use of cognitive behavioural therapy (CBT) models in grief work are drawing on lessons learned in PTSD treatment. However, models used in grief work, such as attachment, the Dual Process Model (Stroebe & Schut, 1999) and Psychosocial Transition Theory (Parkes, 1993), are less commonly applied to understanding and treating PTSD. This paper gives an overview of how these theories explain complicated grief and PTSD and considers implications they have on treatment of couples, based on literature review and clinical experience. Treatment implications include treating PTSD before traumatic grief, working with intra-couple coping style differences, promoting acceptance and forgiveness and taking a full attachment history.