In a one-to-one therapeutic relationship, the primary dynamic is that between the client and the therapist. We are of course also each in relationship with ourselves, and the pursuit of therapy is to understand more about how the client relates to both themselves and others, to put them at choice about how they may wish to develop this inner and outer rapport.
The difference in couples work is that the 'other' that the client is relating to is also in the room. Three people's conscious and unconscious processes are at play, making the process both more complex, and at the same time more simple.
The simplicity comes from the immediacy of feedback. For everything one partner says, there is another, real-time perspective. This means there is much richer information available, and sometimes a greater degree of honesty about what is happening outside the therapy room. To pull the wool over a therapist's eyes now takes two willing participants, who knows if your partner will or will not collude?! This increased information seems to move the therapy along more quickly than individual work, insights tend to come faster and deeper, and commitments to change can be made more rapidly.
The complexity in couples work comes from two people each bringing their own history, thoughts and feelings into the room. We all project our inner world onto the people around us, most especially our intimate partner. In a one to one counselling relationship there is one client bringing their way of being to the therapy, with couples there is twice the material to work with. The good news is that couples can not do other than play out their way of being in therapy, as they do everywhere else. The observer in the system, the therapist, is able to provide a third perspective, and that third perspective changes the couple dynamic.
Couples counselling involves the therapist providing a framework for working, and perhaps teaching skills along with exploring experiences. In this way it may feel more directed, although all interventions are intended to work towards the goals the couple bring.
Like any therapy, couples counselling can be intense, moving, and challenging. It's benefits can be significant, it may bring personal growth and learning along with improved relating. Like any kind of intervention, it is not without its risks. Before going to couples counselling it is a good idea to be clear what you want to achieve, and what you are prepared to do, and let go of, to bring about change.