Even if you get married, what do you do? You bring a man or a woman to your house, or you move to his house, sharing a common bed and gaining the authority to slip your hand inside somebody’s pants. Even the courts of law call that as consummation of marriage. Live-in is an unofficial marriage; live-in is a marriage not sanctioned by society. Otherwise, tell me, what really is the difference? And many of the live-in couples would marry if marriage were to be made possible to them.
Married couples fight. And there have been so many reports of live-in partners not merely fighting but actually assaulting each other, and even killing each other.