Hebrews chapter 13:4 God said marriage is honourable the bed undefiled, is not a statement but a command from God. Sex is only for the married, there is no justification for it outside marriage.
But so that you will know what really happens during fornication and adultery this message is very necessary. May be when people know
what actually takes place when they disobey God they may have a rethink. Man is made up of the spirit, the soul and the body. The body is the physical you, your spirit is the real you while the soul is made up of your mind, emotion and will. And sex is the only thing you do with your spirit, soul and body at the same time. So God designed sex only for marriage because the man and his wife are one. Genesis 2:24,
Matthew 19:5, Mark 10:7. He didn’t say the man and His girlfriend or fiancée, marriage makes two people one and sex unites their spirit, soul and body together. So you can see how dangerous it is to be having sex with someone you are not yet married to, or sleeping with different people. Pre-marital sex does not just kill love, it reduces your soul, your mind and mental faculty diminishes, your emotion becomes unstable and then your will is weak.
When a man marries a woman, sex makes them better, their capacity is increased. Ecclesiastes
4:9-12. If fornicating with a person reduces
your soul, now imagine what happens when a
person begins to sleep around. It is not fun; it is the manipulation of the devil to destroy your soul. Sampson could not reason well as he
continued in adultery with Delilah. A part of your soul goes with the person you sleep with, no wonder when there is a break-up of that
relationship you may still keep seeing that
fellow in dreams, unless you take that part of you in that person through sincere prayers and repentance you may not really reach the
maximum of your destiny. This is why even after marriage most people still find themselves lusting after their EX. Sex is not just a commitment it is a spiritual transaction. No wonder it is advisable to flee fornication and lusts. Destinies are being reduced through the instrumentality of fornication and the devil is making a big gain out of this because people don’t know that when you have sex with a person other than your wife/husband you’ve just enslaved your destiny, that person have taken a part of you and you’ve taken a part of that person also. Even when you stop having sex and break-up you need to consciously retrieve that part that is in that person. Proverbs 11:9 says through knowledge shall the just be delivered. It is time to stop the devil from controlling your mind. The truth you know and do something about can make you free. John 8:32. The devil manipulates the minds of people just to make them feel they can’t do without sex, he pollutes their minds with indecency music and many more. So they eventually become sex slave not being able to flee and say no, but it is time to arise. Right now if you are involved in pre-marital sex it is time to stop and take that part of you that you sold through fornication and God will restore you back in the name of Jesus. Joel 2:25, God can restore but that is not until you truly repent and pray with the understanding of what happens during fornication.

Furthermore, man’s sperm is not supposed to be spilled and wasted; it’s a spiritual raw material for procreation invented by God. It is dangerous to waste it, God hates waste.
Genesis 38:7-9. If you don’t deal with past sex experiences, your marriage may be affected because you cannot really commit your total self to your spouse and when there is a sex problem there will be a communication problem in marriage. Please pass this message to many people . You never can tell how many people’s mindset will change for the better through the conviction of the Holy Spirit.
God bless you.