Let's get some real separation of Church and State, here, and some real clarity.

The Church is within its rights to declare that it will limit marriage to those between a man and a woman.

The States can declare Civil Unions between two people of the same sex, if they wish, and so can the Federal Government (and they have).

Individuals in the US an arrange their lives as they see fit. They can throw a party with whatever decorations they see fit, for any reason or no reason, and issue invitation as they see fit. They can name their relationship as they see fit.

Individuals in the US can also arrange for their mutual care through various kinds of contracts, and homosexuals have exactly the same rights as heterosexuals. They can designate whoever they want as beneficiaries, decide who has power of attorney in the event of an emergency, who inherits under their wills, etc.

Some people think that the rights of a married couple in the US are somehow "automatic." This is not true. Everything that is important is in writing, and there are piles of paper to prove it.