"I am guiltless"??

I had the opportunity to attend a Holy Matrimony service recently and I wanted to share a thought that lingered in my mind.

Towards the end of the service, the chief celebrant takes the right hand of the bride,places it in the right hand of the groom , sends them off as husband and wife, and says "Let God be the mediator between you and me, that if you break any of the laws of God, I shall be guiltless."

Basically, I see this as a scene where the chief celebrant is washing himself off any responsibility in the (potential) sin of the newly wed. I wonder why? What is the nature of this "sin" that was significant enough for this part to be included in the public ceremony of this Holy Sacrament?

I want to make my point clearer by pointing to other Sacraments we have.

After administering the Holy Qurbana to the faithful, which is the distribution of the very Holy Body and Blood of the Savior Himself, (and this Holy Sacrament is administered after the rite of forgiveness of all sins is done (through Holy Confession or Hoosoyo)) - after this Sacrament is administered, the chief celebrant does not say - "I am guiltless" of any further sin by you. The
faithful typically sins again, is again forgiven, and is again given Holy Qurbana.

Pilate washing hands

After administering the sacrament of Holy Baptism, which is the act of actually grafting the new member (be it a baby or an adult) into the very Body of Christ which is the Holy Church, the celebrant does not say "I am guiltless" of any further sins by this new member of the Body, which may lessen the glow of the Holy Spirit in him.

I have never witnessed a Sacrament of Holy Ordination, but from what I have known, I do not think that the chief celebrant who ordains the new candidates into holy Priesthood then says "he is guiltless" of any future sins the newly ordained priest may commit (sins which may be against the very faith of the Holy Church).

Why then is it that only for the Sacrament of Holy Matrimony where we have a very public section where the Church is seen washing her hands off the lives of  the newly wed, basically telling them that they are now on their own.

Is this symbolic act not contradictory to the idea of the Church which should be the comforter and last friend and resort of every sinner? Yet here we see the Church represented by the chief celebrant first creating a new home, ordaining the King and Queen of the home, and then immediately withdrawing itself from the accountability in the home saying "I am guiltless". Shouldn't he rather be
saying "Do not sin, for I too will be held accountable for your sin on the last day"?

Maybe I am missing something, please educate me. Hoping to hear your thoughts.

Source: ICON