We now recognize that families are complex in their relationships. In a family, the "patient" is not the only one who is affected by the illness. Each member of the family plays a role, although the patient is the "star." Thus the basis for the field of family therapy, in which the entire family is treated. Today, with the multiple models for the family unit, a more apt term might be household therapy.
The central theme is that without therapy, other family members function as enablers. By helping the ill person deal with the chronic illness, the others eventually come to define their existence and derive purpose in life from their supporting roles to the patient-star. This is the nature of that well-known phenomenon, codependency.