That is a misconception. Just because it was in the Bible, that doesn't mean it was commanded by God. The Bible also gives us reference to the culture of the time. In the culture and religiously, it was considered wrong to have premaritial sex. In fact if you was a woman who had sex and was not yet married, chances are you would never get married. That is when they setup the law to state that the rapist would pay half of the amount they normally would to take the victim as their wife, with a couple of regulations. The woman was allowed to refuse to marry her rapist and the rapist had to perform every responsibility a husband was required (provide protection, food, shelter, ect) but was not allowed to sleep with her unless she gave him permission. If you were to take the time to study the culture for back then you would understand that. But just assuming it was part of God's law because it was in the Bible just makes you look like a fool.