Whoever divorces … and marries another … commits adultery: The parallel in Luke 16:18 agrees with Mark and mentions no exceptions to this prohibition of divorce. But Matthew's passage allows an exception when one spouse commits adultery (Matthew 19:9; see also 5:32). The apostle Paul also allows an exception if an unbelieving spouse leaves the marriage (1 Corinthians 7:15).
Mark’s account focuses on the main teachings about marriage and divorce:
God hates divorce (Malachi 2:16),
marriage is meant to last for life, and
divorce goes against God’s purpose for marriage.