Nah, not the derailing. Whether or not marriage is a progressive institution is not the question here, Mr Campbell, why one sect of the society is allowed to engage in it and enjoy its benefits, but others aren't is.

Why are you, as a heterosexual man, allowed to marry the love of your life but a lesbian couple aren't? Why is their marriage looked down upon while yours is looked up to?

Why can't gay people adhere to traditions they believe to be true? Why must one be heterosexual to want to have an official ceremony of their union? Traditions are nothing more than social norms followed by a bunch of people for a bunch of years. They can change, much like how everything else does.

Not to mention, it's stupid to make heterosexual marriages as the paragon of happy and successful marriages when many times the two people in them aren't even happy.