How come two people committing to one another is such an awful thing in so many places?

Christian Science Monitor: "The resounding "no" that voters gave to officially recognizing homosexual couples as married marks a major setback for the gay-marriage movement - and shows how the issue continues to divide the nation politically and geographically.
In all 11 states where they were on the ballot, measures banning same-sex marriage won - in most states overwhelmingly. Even in socially liberal Oregon, where gay-rights activists poured resources into defeating the measure, it passed handily. The other states where the measure passed were Arkansas, Georgia, Kentucky, Michigan, Mississippi, Montana, North Dakota, Ohio, Oklahoma, and Utah."

Another example of my blue-state brain not comprehending, not even beginning to be able to conceptualise, the red state logic that pushed this through.