A concept called “co-dependence” is proposed as describing the social relationships in the modern age. This concept, originally conceived in the field of therapy of addictions, can be available as a sociological concept which presents a model of social relationships. However, this concept is partially problematic for applying to the field of sociology because it is originally conceived in the field of clinics. It will be necessary to solve these problems for the further application of this concept in the theory of social relationships.