I wanted to come out of lurkdom to say that sometimes there is a reason people can't get married or live together. My other half has spina bifida and when we moved in together the government took away his disability benefits, saying that together our income was too high. My other half and I are lucky right now because both of us are working and have pretty decent benefits through our jobs, but others are not so lucky. I do know people in the disabled community who will never live with or marry their significant others because the government will take away what little benefits they have. Not trying to be snarky, but just wanted to point out another side that abled-bodied people may not see.
I completely agree. This is a perfect example of what I meant by “There are many other kinds of cases that just about anyone would agree should be treated as social units.”
I'm so sorry, I went back to re-read your post and I see that now! After a while it feels like people are being bashed for not getting married, and I wanted to point out that there can be good reasons why. And, honestly, if someone doesn't want to get married "just because they don't", I respect that, too. If someone didn't want to treat my other half and I as a social unit just because we aren't married, I would have no issues cutting that person out of my life or, at least limiting contact. Luckily, the people we know don't seem to think that way.