It should definitely been seen as an historical book. And every time you see a weird rule like this, you have to remind yourself that it was being instituted to improve the situation.

In this case, it’s likely that the extant rule was that girls who had been raped were to be banished from the community, or worse. This rule guaranteed she would still have a home and protector. Not a great one, but still an improvement.

A similar thing happens in the story where Abram is told to sacrifice Isaac, but is given a reprieve at the last moment.

You can see this as evidence that God is sadistic. Read through our eyes, it looks that way. It’s likely that child sacrifice was common in that time and place, so this story tells something else: it’s telling people to start sacrificing animals instead of children, and putting a divine stamp on the instruction.

Again, not great, but a huge improvement.