Couples therapy can be a useful method of intervention for couples that are having difficulty communicating or working through serious issues. A skilled couples therapist can help identify problematic patterns of behavior/ communication and help build on strengths in the relationship.
Not all couples therapy is about staying together. Sometimes therapy can be about separating in the most healthy way for the couple, especially if there are children involved. It is important to recognize that every couple is different and has different goals in mind when they are in couples therapy.