In a sense much of this is about whether the established dictionary definition of marriage needs to be modified, so as to cover both partnerships between members of opposite sexes and partnerships between members of the same sex, or whether a different expression - such as civil partnership - should be used.

Generally speaking changes in dictionary definitions follow a change in the way people use the word, and I think there is a lot to be said for that being done in this case too. If the modified meaning catches on, stick it in the next edition of the dictionary.

I see that though in England same civil sex partnerships are not formally referred to as marriages - but that on one case where a women entered into a civil partnership and it turned out she was still legally married (to a man), she was charged with bigamy. Which in a way rather implies equivalent status for the two types of partnership, whatever they may be called.