And it was said, Whoever divorces his wife, let him give her a certificate of divorce.
But I say to you that every one who divorces his wife, except for the cause of fornication, causes her to commit adultery, and whoever marries her who has been divorced commits adultery.
According to the word of the Lord Jesus, the only cause for divorce is fornication. Only two things can break the marriage tie: either the death of one of the parties or fornication, adultery. If either party commits adultery, the marriage tie is broken. This is the principle. Therefore, the Lord Jesus said that there must be no divorce except in the case of fornication. But you should not take advantage of this as an excuse to remarry simply because an act of fornication has been committed. This also is a matter of motive. If possible, the offending one should be forgiven. However, it is different if the guilty party refuses to repent and lives in that kind of sin or marries someone else. In such a case as this, the marriage tie is broken, and the other party is free.
In His original design for marriage, God ordained one wife for one husband. Hence, the Lord Jesus as the King of the heavenly kingdom brings the matter of marriage back to the beginning.