While it’s true that God’s instruction to Adam was to be “fruitful and multiply, and fill the earth”, that was His mandate for the entire race, not just Adam and Eve. That is not, however, the primary function of marriage. As we read in Genesis 2:18, “The Lord God said, ‘It is not good that the man should be alone; I will make him a helper fitting for him’.”
There is an interesting sequence of events recorded just after that verse. God had created the birds and land animals. After creating Adam, He brought the animals before Adam to be named. I can picture Adam seeing the birds and other animals and noticing that they were in pairs. The almost inevitable result would be that he saw the animals with their mates but realized he didn’t have one. It doesn’t tell us that God brought the animals before Adam in pairs, but I’m pretty sure Adam somehow realized there were boy animals and girl animals. It would be like God to do something like that: He so often creates a need or a longing in our hearts that He alone can fill. Adam sensed an unmet need, an unfulfilled longing, and God provided the means to fill it. When Adam saw Eve for the first time, he was convinced she was the most beautiful woman he had ever seen. If he was smart—which he was—he would almost certainly have told her that. And he wouldn’t have been lying, because she was the only woman he had ever seen.
I remember another couple in that same church. I had married them, and they were two very sweet Christians. The only real disappointment in their marriage was they were unable to have children, something they longed for. Their marriage, however, was one of the happiest and most fulfilling I have ever witnessed. They were deeply in love with each other and God’s blessing on their life together was evident. If procreation was the primary function of marriage, then how was it possible for them to be so happy? Because the main purpose of marriage is companionship, and that they had in full measure.
While we’re on the subject, were you aware that while the husband is told to love his wife just as Christ loved the church, the wife is never given the same instruction? Titus 2:4 does state that “the young women [are] to love their husbands”, but a different word is used. The Lord’s instruction to the husband is found in Ephesians 5:25, where the word “love” is translated from the Greek agapeo [pronounced ah-guh-PEH-o]. It is the highest form of love: unselfish, ready and willing to serve. The husband is to love his wife in the same way that Christ loved the church. The word translated as “love” in Titus, however, is the Greek word phileo, which signifies affection characterized by faithfulness and constancy…sort of like, well, companionship.