If anything, it will help to alleviate the promiscuousness among gays that many here are always opining about. The libertarian in me says it's just not such a major issue. Life will go on even if gays are allowed to marry.
But while the issue is up for discussion, it seems many "pro-family" organizations are seeing a fundraising bonanza. But that's just the cynic in me talking.
B.S. If they're so promiscuous and unfaithful to their partners without a piece of paper, it's going to be no different with it.