It wouldn’t be a marriage. We already have a name for it:
friendship. Why create ambiguity by making definitions more murky than they already are?
Marriage is the lifelong commitment of a man and woman who come together for the procreative intent of having offspring and caring for each other and their progeny.
Why does this need to be redefined?
Come up with new words to define some other state, but why redefine something that has a reality of its own? A same sex union or some other “loving” relationship is not what is adequately defined above as marriage. These other states mean something else, quite entirely.
There might be legal justification for extending something like tax or beneficiary benefits to other relationships, but there is no need to redefine the meaning of marriage, just change tax laws to include other relationships under the law. What is the point of muddling terms?
While we’re at it, let’s call all animals, “humans,” all planets, “Earths” and all cars, “Buicks,” just because we don’t like definitional precision. It’s nonsense. If we’re really thorough, we could trim the English dictionary down to just a few thousand words.