The work is intended to show that theological reflection on family and marriage is of great relevance in the context of social change and must continue to develop in a constant dialog with new realities of life. The following questions were investigated: Is there a need on the part of the Catholic Church for an expanded theology of marriage and family in order to take adequate account of the new forms of family in society? Is there a possibility of a rapprochement between the principles of the Catholic Church and polyamorous life concepts, and if so, under what conditions could such a rapprochement take place? The results of this work show that an expanded theology of marriage and family is necessary in order to do justice to the diverse family structures in society. Due to its traditional teachings and principles of faith, the Catholic Church faces considerable challenges when it comes to considering polyamory as a new form of family. In addition, starting points for a further development within the teachings of the Catholic Church and an accompanying rapprochement of the different lifeworlds are identified.