Urgh, that piece reads as if it's trying to be cleverer than it really is (not sure why - the author must be clever, surely?)
Just to play devil's advocate a little with something OldCrone said upthread: "Why should the rest of society have to agree to a major change in a person's legal status because they have made a lifestyle choice?"
Arguably marriage is a lifestyle choice, which the rest of society has to accept and to which certain status and benefits are awarded.
However, society also gets to make the rules about what constitutes a legal marriage (and this varies immensely from culture to culture, country to country) and anyone who tried to say "but I'm a wife because I say I am!" would be laughed at not pandered to.