The Bible’s answer
The Bible clearly states that “
God will judge fornicators.” (Hebrews 13:4) The Greek word for “fornication,” por·neiʹa, includes premarital sex. Therefore, it would be wrong in God’s eyes for an unmarried couple to live together—even if they intend to get married later.
What if a couple are deeply in love? God still requires that they marry before having sex. It was God who created us with the capacity to love. God’s primary quality is love. (1 John 4:8) Therefore, he has good reason for insisting that sex be reserved for married couples.