For this reason a man will leave his father and mother and be united to his wife, and they will become one flesh. — Genesis 2:24.
We are different! God made us male and female so we can be complements of each other. Each of us, male or female, is made in God’s image. God intends that a husband and wife find their primary intimate human relationship with the other. They still honor their parents, but their home is with each other. Their two lives become one. They know each other intimately and share that intimacy across many facets of their lives. In this context of lifetime security and commitment, they share in the intimate knowledge of each other sexually — becoming “one flesh” and fully knowing each other deeply. This relationship is to be enjoyed (Proverbs 5), protected (1 Thessalonians 4:3-8), and celebrated (Song of Solomon) for life (Matthew 19:6).