In some relationships, arguments always seem one sided — with one partner making all the noise as the other quietly calms the storm. It’s possible they both have a problem expressing their feelings, but together they’re able to reassure each other that emotions are being managed.
Different couples will experience it in different ways, but that inexplicable feeling of wholeness you have when you’re together is what Henry Dicks, a guru in relationship psychotherapy, called the "unconscious fit".