Has anybody ever listed specific ways in which gay marriage allegedly screws up other marriages? I haven't noticed a problem, but maybe it's just me.

If you don't like gay marriage, don't get gay-married.

(But by the same token, a church that objects to gay marriage on doctrinal grounds shouldn't be compelled by law to marry gay couples. In fact, separation of church and state guarantees it won't be. If some gay couples demand a church wedding, that's a private issue between them and their church.)