Don't get it twisted, God could have programed man to be procreative without giving him or her physical feelings, or emotion. Or any of the rituals that follow leading to the life breathed into generations to come. We did not have to have eyes to see a temptation be it male or female. We did not have to size someone up, deciding weather or not he or she would be a good "catch". God did not have to give us the power to do any of it. But he did. We have choices. Our metaphysical being seeks someone whose chemistry is attracted to ours. It is really not as complicated as it seems. The complication comes after the physical becomes a continued thing. Our brains began to think how can we keep this same metaphysical thing going. And so it begins.
1 Corinthians 7:2 But because of the temptation to sexual immorality, each man should have his own wife and each woman her own husband.
1 Corinthians 6:9-10 Or do you not know that the unrighteous will not inherit the kingdom of God? Do not be deceived: neither the sexually immoral, nor idolaters, nor adulterers, nor men who practice homosexuality. Nor thieves, or the greedy, nor drunkards, nor revilers, nor swindlers will inherit the kingdom of God.