It is useful to make a slight distinction between therapy and counseling. Therapy is defined as "treatment intended to heal or relieve a disorder." Counseling, is defined as "the provision of assistance and guidance in resolving personal, social, or psychological problems and difficulties." Counseling's definition does not assume that a "disorder" must be present. Hence we refer to "pre-marital counseling" not "pre-marital therapy".
Whether couples seek counseling through their place of worship or through a trained clinician, pre-marital counseling provides a valuable platform to ensure that each person knows as much as possible about the other before making what will hopefully be a life-long commitment. (The clinician should have either certification or a license specific to couples therapy.)
Pre-marital counseling should be a place where each person acknowledges what they anticipate will be their relationship's greatest strengths and greatest challenges. A common fantasy that engaged couples may have is that certain challenges will resolve or disappear simply through the act of marrying. This is rarely if ever the case. In fact, most couples struggle with the same challenges throughout their marriage. What distinguishes the healthy marriages is an ability to take these challenges to a different level so that, over time, they become less problematic. Pre-marital counseling can be a safe place to identify these assumptions if they exist and to explore such assumptions sooner, rather than later.
For many couples, pre-marital counseling is a positive, affirming and bonding experience that enhances their commitment to marry. It is so easy to get carried away with meaningless but pressing details such as which cake flavor to choose, what floral arrangement works best and whether to send out save-the-date notifications. Pre-Marital Counseling can help couples keep their priorities grounded and focused on what the wedding preparations represent -- the decision to build a life together.
If you are engaged or contemplating engagement and do not plan to pursue pre-marital counseling, be sure to read Elizabeth Gilbert's Committed: A Skeptic Makes Peace with Marriage and Monica Mendez Leahy's 1001 Questions to Ask Before You Get Married. Many of my clients have found these resources incredibly helpful. If you are happily married but toying with the idea of couples therapy, be sure to read Elizabeth Weil's book No Cheating, No Dying: I Had a Good Marriage. Then I Tried To Make It Better.
Sometimes a good book can be a great friend and can save you time, money and emotional energy.