I found this article on the PTSD website and thought it might help some of us here:
Trauma survivors with PTSD may have trouble with their close family relationships or friendships. The symptoms of PTSD can cause problems with trust, closeness, communication, and problem solving. These problems may affect the way the survivor acts with others. In turn, the way a loved one responds to him or her affects the trauma survivor. A circular pattern can develop that may sometimes harm relationships.