Who takes marriage most seriously?

A columnist at the HuffPo writes about her thoughts upon attending her gay brother's wedding.  And about what she learned about "the sanctity of marriage".

Weddings mark the start of a shared union -- a lifelong partnership between two people who have chosen to make binding promises to one another. Promises that often involve agreeing to work on the marriage when it needs to be worked on and to fight for it when it needs to be fought for. 

And if I had to guess which couples would be likely to work and fight the hardest for their marriages, I would predict it to be those who have already worked hard and fought to make marrying their partners a possibility in the first place. 

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Marriage is, indeed, sacred. But if proponents of traditional marriage are truly worried about sanctity, doesn't taking marriage away from those who likely revere it the most -- the same-sex couples like my brother and his husband whose ceremonies are far more focused on the extreme gratitude over their ability to be legally recognized in marriage than the cosmetic details of the day -- seem to contradict what they are after?