As some food for thought, since it was brought up that "marriage" as a word stems from "mater". The German equivalent is "Ehe" stemming from "law" and "conventions".
In Germany itself the "Ehe" is only for heterosexual pairs, but is a matter of the state. A marriage in Church doesn't count as a legal marriage. You have to get married by an official of the state first, before you can get married in a church (if you want).
There is a status similar (civil union) to marriage for same-sex pairings.
It currently doesn't give all legal benefits marriage has (they aren't equal in taxation and adoption, for example), but the highest court has ruled, that while the "Ehe" is especially protected by the Grundgesetz (similar to the Constitution), the legislation is well within their rights to grant/demand to/from same-sex civil unions the same benefits/duties as married pairs.
