To engage in premarital or extramarital sex, before or outside of marriage, is to sin in Gods sight. Using the bed aside from marriage is sin that God will judge The counsel given in 1 Corinthians 7:9 makes the same point.

What does the Bible says about sex before marriage?

What is written about sex before marriage in the Bible comes predominantly from the book of 1 Corinthians, written by Paul. 1 Corinthians 6:18-20 says “Flee from sexual immorality. Every other sin a person commits is outside the body, but the sexually immoral person sins against his own body.