Rodney

Actually, if you want to go back to the roots, marriage is basically an alliance meant to pool and preserve the resources of two families. Each side brings some of the wealth of the family, and there are contracts to prevent one side from running off with all the loot. Makes sense, especially if the assets are farm land; with each generation, as each new person marries in, in theory the wealth grows greater (especially if the oldest son inherits most of the property, as was often customary).

Even today, that's a lot of what it's about. If two people pool their resources in a relationship, it helps for there to be rules that cover all eventualities -- divorce, incapacity, death, etc. You may think that religious types are the most fervent defenders of marriage, but they're not. It's the lawyers and accountants.

I was buying a house once with the woman I was living with (we married later). She had shit credit, so the mortgage was in my name even though she was paying her share of the payments and eventually caught me up on her share of the down. Anyway, I mentioned this to my accountant and a real estate lawyer while I was doing the deal, and they both broke out into a sweat (the accountant literally did -- a nervous guy) and _strongly_ urged me to get married. They had apparently been involved in lawsuits and forensic accounting with living-together couples who split up and then had to split property bought under informal arrangements like mine. "It can get really, really ugly," my sweating accountant said. The lawyer said, "Marriage is a package of rights and responsibilities that governs the affairs of two people. You can try to recreate it outside of marriage by a series of individual agreements, but there's always the potential for problems."

In sum: you may or may not believe in marriage; but if you're going to live with somebody and pool resources, you need protection. Marriage is one easy way (depending on the state, of course). With maybe a good prenup also, depending on the situation.