I agree with this. Anger is often a defense mechanism.

For example: A person applies for a job and does nor get the job. This particular person might feel humiliation, shame, rejection, helplessness at their lack of success. If such feelings tend to become too painful to tolerate, anger can arise to cover up those feelings.

A good therapist would be aware of this. She might try to uncover and address the underlying issues that give rise to such intense feelings. She might try to help the person gain strength so as to deal with feelings that arise after setbacks, such that the anger can be controlled.

There could also be gender issues involved. A guy might feel emasculated if he does not get his way with his partner. Here, your boyfriend could feel emasculated due to the interventions of family members. The felt shame connected with feeling emasculated could well be covered up by anger. A good therapist would be aware of this possibility as well.