In this paper an attempt is made to demonstrate how a particular orientation to contemporary psychoanalytic concepts may be useful to an understanding of the nature of the marital, or couple, relationship. The unconscious forces which may attract two people to each other, which may influence the patterns of their interaction and which may result in psychic stagnation or development are outlined. The second part of the paper addresses the nature of the therapeutic relationship with the patient couple. A hypothesis is offered regarding possible diagnostic criteria for choosing whether to work with a couple presenting for couple psychotherapy employing one psychotherapist or two psychotherapists working as a co-therapy pair. (The usual practice of myself and my colleagues at the Tavistock Institute of Marital Studies is to see our patient couples with a co-therapist partner).