Jurisdiction Of Govt. In Law Making
Zina with consent makes one unfaithful to one’s spouse, affect the family institution and thus makes the children suffer for having divuded attention. That is why even the otherwise very open society of West doesn’t allow extramarital relation. So it is haq talfi. For the same reason is not allowed to unmarried too in Islam. Here it is for Sadd e zarya, preventive measure. What has to be forbidden after marriage needs to be avoided before marriage too.