No Longer Two But One Flesh
Many of Jesus' teachings were challenging to his followers.
When asked about divorce and why Moses would allow for this reality, Jesus seemingly evades the question, but his actually pointing back to the beginning of Genesis to how God created marriage to be:
"...from the beginning of creation, God made them male and female.
For this reason a man shall leave his father and mother
and be joined to his wife,
and the two shall become one flesh.
So they are no longer two but one flesh.
Therefore what God has joined together,
no human being must separate."