God needs to be the fountain of living waters to us because He has an economy. What is God's economy? God's economy is to have an expression of Himself. God does not want to express Himself by Himself alone; rather, He wants to express Himself through His counterpart. For this reason, God created man and put him in the garden of Eden. Eventually, God said, "It is not good that the man should be alone" (Gen. 2:18a). In typology this signifies that it is not good for God to be alone. This indicates that the first husband mentioned in the Bible was not a human being but God. Who is His counterpart? Adam, who was created in God's image, was to be God's counterpart. In order to be God's counterpart, Adam had to drink of God, to receive God into him that he might have the divine life with the divine nature and the divine element in order to be divine to match God. Because God, the Husband, is divine, the wife, His counterpart, should also be divine that she might match Him. Since it was not good for the man to be alone, God builded from Adam's rib a woman to match him (Gen. 2:21-23).
I would emphasize the fact that God needs to be the fountain of living waters to His elect because He has an economy, and His economy is to produce a counterpart, a bride, for Himself. The purpose of God's economy is that God would no longer be alone but would have a wife to be His increase, His enlargement, and thus to match Him as the Husband. This is the significance of the word increase in John 3:30. In this verse John the Baptist, speaking of Christ, says, "He must increase." In the previous verse John had said, "He who has the bride is the bridegroom." The increase in verse 30 is the bride in verse 29. The Bridegroom is Christ, and the bride is His increase, His enlargement. Just as Eve was the increase of Adam, being built from Adam's rib, so God's elect as the bride are the increase of Christ as the Bridegroom.
God intended to dispense Himself into man as man's satisfaction that God might be enlarged, but man became unfaithful and unchaste and forsook God for idols. This forsaking of God began in the garden of Eden. Eve, the wife of Adam, was not faithful to God but was seduced by the serpent to turn from God to Satan, symbolized by the tree of the knowledge of good and evil. Through Eve Adam also was seduced and ate of the fruit of the tree of knowledge. In this way man turned away from God to idols. Every branch of the tree of knowledge is an idol. Whatever we possess, and even whatever we are, can be an idol. Israel was evil and unfaithful to God in forsaking God for idols. In the matter of such unfaithfulness to God, we are the same as Israel.