The only question really up for decision is how society as a whole shall view these two concepts of the word. Should it confer the word, and the concept, on any fully committed relationship between two people who love each other? Or should the word "marriage" be reserved for the relationship between a man and a woman who are, at least theoretically, capable of having children and raising a family?
Personally, I would not be opposed to the latter solution. It would preserve the word "marriage" for relationships of the traditional sort, thus continuing to confer upon it a particular status. Say a "higher" status if you wish (as do those who object to the idea), but, if so, it is a status that every society has recognized as promoting its own survival.
But I recognize, too, that such a status is not desirable, or even possible, for many people who regard their own status as devalued as a result. And it seems clear that many Americans, in what they regard as a spirit of fairness, are moving toward recognizing the word "marriage" as applying to any two people who want to use it to define their own particular relationship.