Wrong again.
The unity in a marriage begins at the wedding and should increase unceasingly until one of the persons dies.
The unity in marriage must be a foretaste of the unity that we desire with God, now and in the hereafter.
The unity in the marriage should mimic the unity shared among the Three Persons of the Trinity.
That’s why the wedding should be done within the Mass.
The Sacrament of Confession is - well - another act of communion, a re-union, not just with God, and not just with His Church, but with others who we have offended, and even more…the Sacarment of Confession spurs on an interior reunion with our will, our intellect, our conscience, our appetites/emotions, and our body.
And so…the “unity” of the Mariage is PART OF the unity that God has with Himself and wants to share with each of us, present at the wedding or not.