Thoughts from Matthew 19
The Pharisees asked Jesus about divorce, but whether it is permissible or not is not Jesus focus: it’s theirs. Instead, he twice refers them to the beginning, when it was not so. They bring up Moses, and Jesus dismisses Moses and the Law by essentially telling them that God’s purpose from the beginning is more important even than the Law.
The key is God’s design from the beginning. That’s the level Jesus wants from his people, which is consistent with all of Matthew: Jesus constantly calls people to be better than the Law, better than the Pharisees, but not by doing more righteous acts. Rather, his followers need to be devoted to being like God---and his plan---from the beginning, when marriage was about closeness, not separation.