The book of Matthew was written to Jews who had the custom of divorcing from the betrothal, which is why the word "fornication" was used instead of "immorality" or "adultery."
In the other gospels, this exception for divorce was not mentioned because the gentiles had no custom of divorcing from the betrothal, meaning engagement.
1 Corinthians 7:10-12 "…10 To the married I give this command (not I, but the Lord): A wife must not separate from her husband. 11 But if she does, she must remain unmarried or else be reconciled to her husband. And a husband must not divorce his wife. 12 To the rest I say this (I, not the Lord): If a brother has an unbelieving wife and she is willing to live with him, he must not divorce her.…"
Ever since the government allowed for divorce the church followed the world and began to twist the Bible, finding false excuses to allow believers to divorce.
God's Word was clear on many things that the modern apostate church has perverted and accepted.
No one can undo the spiritual bond God makes between two people who make the promise "until death do we part." This spiritual glue that God used to bind two people into one can only be dissolved by God when death occurs.
Mark 10:12
"And if a woman divorces her husband and marries another man, she commits adultery."
1 Corinthians 7:39
"A wife is bound to her husband as long as he lives. But if her husband dies, she is free to be married to whom she wishes, only in the Lord."
Divorce and remarriage is not complicated, these acts are sin against God and the spouse who is put out. The law of the land does not take priority over the Law of God.
The law of the land allows for abortion, but it flies in God's face as does the allowance for divorce and remarriage.
We see what happens when people begin to twist the Bible mixing it with cultural thinking, the law of God is broken and the Christian culture runs amok to disobey God in favor of their own "feelings" and "desires."
It is amazing how many Christians become angry and even rage at those who would tell them what God said. They use every excuse in the societal book to justify what God hates.
Romans 7:3
"Accordingly, she will be called an adulteress if she lives with another man while her husband is alive. But if her husband dies, she is free from that law, and if she marries another man she is not an adulteress."
Malachi 2:16
16 “For I hate divorce,” says the Lord, the God of Israel, “and him who covers his garment with violence,” says the Lord of armies. “So be careful about your spirit, that you do not deal treacherously.”
Why would a born-again believer defend what God hates? Just asking!