The couples themselves represent the inconstancy and virulent nature of some marriages. The couples also represent the dichotomy of social vs. private lives in a marriage.  People often put on "fronts" in public to make others think their marriage is well; however, it is a different story in private.  Also, the portrayal of the couples' relationships smacks of irony as far as tearing apart the idea that marriage is a wonderful, centering, grounding institution.  These couples are anything but centered and grounded!  They fight, make up, fight some more, hold grudges, etc.