Why do men and women get into trouble after having sex?

How do men and also women get into trouble after having sex with each other? I am referring to a first encounter, but it also happens through out a couples relationship.

Fornication is what the problem is. It's not the woman's fault, it's not the man's fault either. God's commandment was broken and now the man and woman have been cursed. That curse is for the devil to attack them. The devil only comes to steal, kill and destroy.

If the couple had been married, then they would not have had the troubles caused by fornication.

Adultery is another one that happens, even when the couple are married. A woman who has left a man for an unjust reason, is committing adultery. Same for a man. Even if the woman or man had been divorced, if it's not for a just reason, which is unfaithfulness or not being of the christian faith.