Well, because I don't live where you live. In my country, the police actually go around raiding hotels at night and if they find a man and a woman who are not married, they are taken to jail. No, there's no law against it, but the police take it upon themselves to do moral policing. They do it by framing the woman for prostitution. It is a "lesson" for unmarried people not to have sex.
No one will rent out a house to you if you are an unmarried couple. If they do, the neighbors will bash up the house owner, so they better not.
Yes, this place sucks. Here, the only way you can get someone to be with you and share your love, life and kids - is marriage. And I dont have the money to get out of this place.
Oh, and none of these rules apply if you are super-rich or a celebrity or a politician. Unfortunately I am not any of those.