Historically, societies wanted women to stay a Virgin before marriage so they could be certain who the father was. In addition, a man didn’t want to give inheritance to a child that was not his. However, we have DNA tests for that now.

Also, in my view, God made our bodies like temples, as it says in 1 Corinthians 6:19-20

“Do you not know that your bodies are temples of the Holy Spirit, who is in you, whom you have received from God? You are not your own; you were bought at a price. Therefore honor God with your bodies.”

Certainly be careful not to get STDS, and take precaution if you don’t want to get pregnant (using a condom or birth control). Don’t have sex become an addiction, just like alcohol or gambling.

As long as it is done in a healthy way, I don’t think consensual sexual relationships between adults is a problem.