Matthew 19:3 The Pharisees also came to Him, testing Him, and saying to Him, “Is it lawful for a man to divorce his wife for just any reason?” 4 And He answered and said to them, “Have you not read that He who made them at the beginning ‘made them male and female,’ 5 and said, ‘For this reason a man shall leave his father and mother and be joined to his wife, and the two shall become one flesh’? 6 So then, they are no longer two but one flesh. Therefore what God has joined together, let not man separate.” 7 They said to Him, “Why then did Moses command to give a certificate of divorce, and to put her away?” 8 He said to them, “Moses, because of the hardness of your hearts, permitted you to divorce your wives, but from the beginning it was not so. 9 And I say to you, whoever divorces his wife, except for sexual immorality, and marries another, commits adultery; and whoever marries her who is divorced commits adultery.”
10 His disciples said to Him, “If such is the case of the man with his wife, it is better not to marry.” 11 But He said to them, “All cannot accept this saying, but only those to whom it has been given: 12 For there are eunuchs who were born thus from their mother’s womb, and there are eunuchs who were made eunuchs by men, and there are eunuchs who have made themselves eunuchs for the kingdom of heaven’s sake. He who is able to accept it, let him accept it.”
Look at the disciples comment. If we [can’t dump or wives for any reason or sleep around], then it’s better not to marry. For some, there may be good reasons not to marry, but God’s marriage laws are not one of them. So growth rates in divorce and sex outside of marriage are a sign of increased hardness of hearts.
Moses permitted divorce because he had a nation of sinners to run. Those with hard hearts cannot accept God’s restrictions on divorce and adultery. But if God helps then (those to whom it has been given), then they are able to accept it, and they should accept it (He who is able to accept it, let him accept it).
So for those facing divorce, I think we have two cases: those who can accept God’s marriage rules and those who can’t. So if we struggle with obeying God’s marriage rules; we should thank God for His graciously enabling us to accept His rules as our standard in the first place. God has not abandoned us to the hardness of heart that rejects and cannot accept His rules. Sometimes the spirit is willing, but the flesh is week, so we must pray not to enter into temptation (Matthew 26:41).
If on the other hand, we cannot accept God’s marriage rules, we really should be asking why not? It is true that God isn’t giving us the grace to be able to accept His marriage rules, but why not? Sometimes we do not have ears to hear, because we are unwilling to receive the message (Matthew 11:14-15). In other words, hardness of heart about God’s marriage laws may betray some deeper stubbornness in our fundamental relationship with God.
Now for those Calvinist who deny free will with respect to God's marriage rules - you have done well, but not gone far enough. You must also get rid of your philosophy which says, a man is able to do something, if he would do it were he to want to. So you're really saying "we can and cannot obey God's rules on divorce". On one side of this contraction you have the implication that man is physically and mentally handicapped when it comes to divorce. On the other, you have the implication that notwithstanding what Christ said, in the normal sense man can accept God's rules on divorce. Without this philosophical obstacle our need for God's grace shines clear.