He gave Adam a pleasant task - to care for this garden. Adam would learn responsibility and the joy of achievement. God gave Adam a companion and helper, Eve. In this we see the true purpose for marriage. It is to be both a physical and a spiritual union.
Marriage is the physical and spiritual union of two people.
Sex for men and women is not simply for the procreation of the species. It is to express physically, the union of the couple's souls. This is why broken relationships are so devastating for the people involved. They don't realise that by indulging in sex, they have actually joined their souls to one another. When the relationship breaks up their souls are torn apart.