By far the most common "presenting problem" I encounter at an initial session with couples is "COMMUNICATION." I've previously written about this vast topic (please see: http://jimwein09.squarespace.com/blog/2010/7/31/communicating-with-your-partner.html ) which has a wide variety of dimensions and ways of manifesting.
A not uncommon characteristic of certain people in relationships (whether romantic, platonic, or familial) is to send signals to the other that there are topics or modes of communication that are so disturbing as to be entirely avoided. I have a dear, longtime friend who is constantly sending these signals to the people closest to her. She so loathes any hint of criticism that she will either terminate communication (sometimes for days or weeks) if she senses that criticism is being implied, or report that the conversation in which she felt criticized was so painful to her that she a) couldn't get out of bed for a whole day; b) spent half the night crying; or c) spent the whole next session with her therapist discussing it. In other words, "Look what you put me through!!"
This is a prime example of attempting to regulate one's inner sense of peace by maneuvering externalities. It can work, but people who use this technique are truly "high maintenance" - and the people who care about them spend so much time and effort tiptoeing around the minefields placed in the path of frank and open dialogue that the quality of the relationship is almost certainly destined to deteriorate. There are most definitely techniques which the "lower maintenance" partner in the relationship can use to make interactions less volatile. For example, requesting rather than demanding or expecting a shift in behavior: "It's so much easier for us to talk about things when we keep in mind how much we love each other and that we're only trying to make things between us even better" vs. "You always get so defensive when I suggest that something might be improved a bit." Or finding ways to relax your high maintenance partner so that the criticism (perceived or real) feels less threatening. Actually, the greater opportunity for relationship improvement is in fact held by the high maintenance partner, as that partner is less "evolved," and at least potentially can significantly "up" his or her relationship game. The problem is that attempts to implement the kinds of techniques that might help achieve this often go awry when the couple is attempting to initiate changes by themselves. The assistance of a marriage / family / relationship therapist enhances the chances of success simply because both halves of the couple are usually able to see that the therapist is objective and neutral, and that suggestions for change are coming from an unslefish, well-intentioned, agenda-less place. Individual therapy for the higher maintenance half of the couple would also make sense, but any outside suggestion that this would be valuable will almost surely be met by indignation.
If you have a friend, wife, husband, child, parent, lover, or partner who is willing to lower his or her resistance to hearing the "truth" about issues as you see them, you will generally find an exponential increase in the honesty with which you are able to communicate. And it is only HONEST communication that can really identify problems and work towards their solution. Too often clients are unwilling to address a genuine problem in their relationships because of the fear of upsetting or hurting the other. Unfortunately, then, the alternative becomes dissembling about or ignoring the problem, which more often than not results in a destructive explosion when the pressure builds and becomes too great due to the unwillingness to identify the "elephant in the room."