The simple understanding of the teaching of Jesus about divorce lies, not so much in the meaning of Hebrew or Greek words, but in the clear statement :-
"What therefore God has joined together, let not man put asunder".(Matt. 19:6)

Once God has joined a marriage, there is no possible ground for its separation by men. It follows that the only union which can be broken is one which has not been joined by God!

It is significant that Matthew's Gospel is the only one to record the "exception clauses".

It is significant also that Matthew is the only New Testament book to contain an EXAMPLE of a proposed divorce. That is of course, the agonising situation in which Joseph was about to divorce Mary for premarital unchastity.

It is the circumstances surrounding this incident, which give us the clue which explains the meaning of "fornication" as a just cause for divorce.

"Fornication" as suspected by Joseph, creates a situation where a marriage is not joined by God, and so provides a basis for men to undo it. This provision has its foundation in the Old Testament.

There were cases in the law of Moses where fornication could render a marriage illegal, and thus invalid.

For example, a priest was commanded to marry only a virgin. (Lev. 21:7).

In such a case, the marriage would have to be undone, to comply with the law. If it was forbidden by God's law, God could never be said to have joined it.

Other men who discovered, after the marriage, that the girl they had married was not a virgin, could also take action. There were two ways in which this could be done.

The first required the girl to be stoned to death. (Deut 22:13-21)

The second, more merciful choice, was to divorce her and send her away. (Deut 24:1) It was this option which had been chosen by Joseph in his dilemma over Mary, the Mother of Jesus.

There was another provision in the law which required a man, who had seduced a girl, to marry her. A girl who had been a party to fornication was not free to marry another man while this obligation remained. (Exodus 22:16)

However, the law also provided for a Jewish father to exercise his right of refusal. Alternatively the first man might die before the wedding, or perhaps the man might already be married. Any of these circumstances would cancel the obligation and the girl would then be free to take another husband, if one could be found.

In such a case honesty would require that the new husband be told in advance that the girl was not a virgin, both to be honest with him and to reassure him that although there had been a divorce, there was no legal barrier to the wedding.

In a 20th century setting, where custom leaves the right of refusal to marry with the girl who has sinned, rather than with her father, it is still true that marriage to another man should not be entered into without proper confession of the situation. Failure to confess, before marriage, that this sin has taken place, amounts to deception, which means that the marriage cannot be truly said to be joined by God.

To say otherwise would make God a party to the lie.

It is for this reason then that Jesus allows for the possibility that a man may need to reconsider his commitment to the marriage. When he becomes aware of the deception, he must decide whether he ought to continue or not.

The fornication and deception, especially if accompanied by an unrepentant and defiant attitude on the part of the girl, would cause most men to decide that they would not have contracted the marriage at all if they had been aware of the situation beforehand .

On the other hand, Jesus does not say that a divorce is mandatory, even for this cause. In a Christian setting, there could certainly be circumstances where genuine repentance on the part of the woman, together with forgiveness on the part of the man, would result in reconciliation and a renewal of commitment to the marriage.

In such a case, ground for divorce would no longer exist. The marriage would now be contracted in truth and honest intention by both parties, and would certainly be joined by God.

Of course, it is obvious that in cases where fornication was known before marriage there would be no cause for divorce for this reason, at any time.

TIMING
By its very nature, this is an issue which ought to be discovered and resolved in the very early days of a marriage.

In most cases, it would become apparent on the wedding night, whether or not the physical tokens of virginity were present. That was the issue in Deuteronomy 22:13-21.

(However caution is needed here. There can sometimes be reasons why these physical tokens would not be found in a girl who was truly a virgin).

It would be rare, and in most cases, almost impossible for this to be a valid cause for divorce after those first few days of a marriage, (especially if there is repentance and forgiveness, when the truth becomes known).