The scribes and pharisees taught based on the authority of their teachers, tracing the tradition of their teaching all the way back to Moses. Today the scribes come to Jesus with what they considered a trick question. They wanted to trip him up publicly so that they could point out that he was a bad teacher, who did not follow tradition and did not come from God. If Jesus says divorce is permitted, he would look bad in the eyes of women. If he says divorce is not permitted, he would be going against the teaching of Moses.
But Jesus responds in a different way. Being the Messiah, he knows the intention of God. Jesus recognizes the authority of Moses but points out that Moses permitted divorce because of the people were hard-hearted. Then Jesus goes back to the original intention of God in the moment of creation. Hard-heartedness and divorce are not part of God’s original intention at the time of the creation. Communion is what characterized the relationship between Adam and Eve before their disobedience. So rather than putting forth a new, anti-divorce teaching, Jesus simply is returning to the original intention of God at creation of man and women. The husband and wife are one. That is the mission of marriage, to be a sign of God love and communion with the human race. Divorce is division and self-centeredness.
The mission and reality of oneness and peace is stamped inside all of us. The mission to renounce ourselves to serve God and others is part of our very being.
The two shall become one flesh.
So, they are no longer two but one flesh.
Image: https://www.kfuo.org/2021/02/26/sharper-iron-the-gospel-in-action-022621-gods-gift-of-marriage/