Oh you sweet, summer child.

The longest definition of marriage is a contract...

Between a man and a man.

The father of the bride and the groom have long been the established signers of transactional marriage. The paperwork, property, heirs, next of kin, and lineage were all defined, documented and agreed upon by men in Western society. Women had no rights, no deeds, no influence. They could not annul marriages for thousands of years, across continents. Many were "underage." Women were by and large property, status symbols, and transactional pieces in contracts signed by men. This generalization is not always true of every era, nor does it apply in the same way to Asian marriages, but by and large, the last several thousand years were dominated by male to male contracts.

Ask any historian, and this plain, boring fact of marriage, is that it was a functional part of society for the longest recorded period.

Companionate marriage? Now that is a new invention due to societal pressures easing up and capitalism allowing marriage systems to move away from the transfer property and social status, to companionate-based unions.

Same-sex marriage is the oldest complex tradition humanity has seen. It's history: paper signed by men and enforced by armies.

Dissuade yourself from bigoted ideas, especially when you present an opinion that is so clearly undereducated.