No, the patient s self diagnosis does not exclude the patient from insurance benefits. Many times patients will describe their problems in terms that do not coincide with diagnostic categories and treatment codes. It is up to the mental health professional to determine if the patients have the symptoms of a DSM-IV diagnosis, and if couples therapy is a treatment of choice. A focus on relationships or marriage does not mean that couples therapy is not treating a DSM IV diagnosis. Mental health is inherently involved with the health of relationships.
Individual therapists discuss marital relationships with their patients.
Family therapists can use marriage counseling techniques. If an insurance company has advertised that it provides mental health benefits, then it is committed to treatments that involve the improvement of relationships. An insurance company has a right to exclude treatments from coverage. It probably could refuse to pay for any Family Therapy that only includes the spouses. However, insurance companies are unlikely to publicly admit to having such a policy because it would demonstrate an irresponsible disregard for an essential mental health service.