From “The Search for the Real Self”, by James F. Masterson MD, chapter 7 “The Challenge of Intimacy”:

“There are all kinds of illusions that make it appear that intimacy is working for a couple, even when, on closer inspection, what we find is not a healthy interchange between two real selves expressing and reinforcing their capacities but a pathologic contract between two false selves which, although it may seem to survive for the moment, inevitably falls apart. A good illustration of this is the couple who always fight in public to the extent that friends wonder why they even stay together. The answer is simple: they stay together because they fight so much. It works for them. The classic example is the case of two borderline personalities who project the withdrawing, disapproving parental image onto each other so that they do not have to feel and be aware of the associated depression. As long as they are angry at their partners, they do not have to feel depressed. For them interpersonal conflict is preferable to feeling intrapsychic depression. If you ask them about their relationship, they are always “having difficulties”; but actually in a pathologic way, it is a relationship that works for them and satisfies the needs of their false selves.

A proof of the pathology behind this kind of “working” relationship is seen in treatment of both borderline and narcissistic patients. When a patient announces that she has found a new lover and that the relationship is comfortable and easy-going, I strongly suspect that the new partner is inappropriate for the patient and is providing a kind of defense against the patient’s painful feelings. On the other hand, if a patient relates that the new relationship is fun and exciting, but also causes a lot of anxiety, I know that new partner is more appropriate and better for the patient in the long run because he is challenging the patient’s old defenses and stimulating the patient to relate in terms of the real self. Anxiety is present because the borderline and narcissistic personalities cannot relate on a realistic level without giving up the defenses of the false self, which in turn makes them feel exposed and vulnerable to the anxiety and depression that they are trying to avoid.”

“Abandonment depression” as the author describes it is what one would feel from early or premature separations from parental love. A synthetic selfhood is created as a fantasy to counteract against the self-belief of inadequacy that needs to be continually reinforced by a series of co-dependent relationships; all in lieu of coming face to face with the “depression from abandonment” or addressing the needs of the real self.