You're having sex premaritally while your hurting your future partner and their future partner. Your choices affect the family name. They affect your reputation when you flirt with another man or woman . Even if they don't know. While you're on your detour unbelievers are watching you and they're deciding about Jesus.
Sin dislocates relationships.
It twists everything around it. It makes a statement about your family, your Lord, and then the storm comes, and it hurts innocent people. You can't sin in a vacuum. You leave an ugly trail of wounded people whenever you live outside of Christ's boundaries. Well, there is pollution spattering everyone around you when you leave the will of God.