It is not "gay" marriage versus traditional marriage that is the larger concern, but the survivability of marriage in general.
The German thinker Nietzsche reminds us in his hard fashion that the institution of marriage requires a more durable foundation (e.g., the property drive, the sex drive, the desire for legitimate heirs, etc. ) than that of fickle romantic love. Marriage, he observes, can never be founded on an individualizing quality ("the way you wear your hat, the way you sip your tea"), any more than a house can stand on shifting sand.
That is why it could be argued that the recent Supreme Court decision granting certain legal rights to homosexual couples does indeed buttress the institution somewhat.
John Clem, Edinburg