How do we know divorce is addressed in the Bible?

In Matthew 5:31-32, Jesus clarifies the Old Testament provisions for divorce, stating that one can only divorce for the cause of fornication. He highlights that the ease of divorce is a result of the hardness of human hearts, referencing that from the beginning, marriage was intended to be a lifelong union between a man and a woman. This teaching affirms the sanctity of marriage and the seriousness of breaking that covenant, urging believers to recognize the spiritual implications of such decisions.