The only nuance I can think of for gay marriage is courthouse vs church. I'm firmly with the Germans and French on this one - 'The state' should not recognize private religious ceremonies.
Everyone should have a civil ceremony/contract signing at the courthouse, and church ceremonies are up to the couple and the church. It's the contract that the state recognizes, not any religious significance.

And if someone's marriage is shaky enough that my marriage can affect it in value or quality, then they've got serious problems.