Prohibition of live-in-relationship doesn't ensure virginity before marriage.
I can't even imagine virginity before marriage any time in the history of the earth.
Live-in-relationship shouldn't confer any rights on the spouse. What about children? These should have rights but it'll be better if the State takes care of them.
Police can't arrest if a man and a woman stay in a hotel and commit sex. Though it's not live-in-relationship, it's not an offence either.