In recent years, many authors have written on the importance of analyzing social support when it comes to understanding PTSD patients. However, the effects of important aspects of the social support construct itself, such as the source of support and its underlying psychosocial processes, remain relatively unexamined. Using a qualitative design, this study sought to explore social support processes between PTSD patients and their relatives. More specifically, thematic and conversational analysis were performed on filmed interactions between 48 PTSD patients and an accompanying person (AP) of their choice. Results indicated that female PTSD patients generally presented a higher frequency of negative interactions than male diagnosed with PTSD. Moreover, couples generally experienced more negative social support compared to non-couples. Finally, it was found that the length of the relationship as well as the onset of the PTSD (before or after the beginning of the relationship) influenced the quality of the interactions for couples in this sample. To our knowledge, this study is one of the few qualitative research that has been made on interactions between PTSD patients and their relatives. This study also offers an innovative point of view on the social processes underlying marital and social support, such as the impact of the length and moment of apparition of romantic relationships on the quality of support offered.