...and what you do afterward, that makes a marriage. Obviously, love and sex are big parts of the equation, for no one would get or stay married without love, and sex is the great gift which not only bonds, but also heals wounds, protects, delights, and comforts in addition to producing children. But I think that at the center of God's purpose for a loving marriage is that it would serve as a tool to make us holy. And making us holy means love mixed in with fights.
If you really think about it, the reason that we fight with our spouses is because of sin, either theirs or ours, and often some of both. Our wounds, inflicted by their sin, lead us into conflict, and seeing the hurt we inflicted on the one we love, when we are repentant, leads us to change so as not to hurt them in the same way again. Meanwhile, forgiveness and grace extended after the fight do their work to bring healing from pain and the elimination of the wall that would otherwise be built between husband and wife, so that further hurt is a possibility, but so is deeper love. Over time, repentance, healing, forgiveness, and love make us look more like Jesus than we would have if we had never loved, and fought with, our beloved.
Thus I can truly say, with Martin Luther, "Marriage did for me what no monastery could."