He does not fight with Himself. A frequent reason given for seeking a divorce is that the original marriage was a mistake. The couple believes that they got married for the wrong reasons and are asking why they should perpetuate a mistake. A deliberate, knowledgeable violation of God's revealed will for marriage is never an appropriate response to a mistake made earlier in life. Two wrongs do not make a right.
Sexual intimacy is the privilege of a marriage relationship.
If the couple is already divorced, such intimacy would be classed as fornication. However, serious consideration should be given by each partner as to their personal motivation in the relationship. One of the considerations a couple must have is their reputation with their children and friends.