@criver "From a societal perspective" is a description that sounds more definitive than it actually is.
Which societal perspective? Societies aren't monolithic, and they contain many groups and individuals with divergent interests. The more or less
dominant societal perspective is often invested precisely in suppressing other societal interests, and it often doesn't even represent the majority. Just what society "wants" or what is "in society's interest" is very much contested. So it sweeps a lot of issues and interests under the rug to say marriage is X "from a societal perspective". Among those are the interests of individuals who place value on love--and there are a lot of such individuals. You can't just say "Oh, what the
people in society want doesn't matter because society"--they
are society.
Meanwhile, speaking as someone who's been married 23 years (and in love, thanks), marriage isn't a contract. Heck, in my country it's not only not reducible to a contract you don't even have to sign one--common law is equivalent for legal purposes and it kicks in automatically after 6 months of cohabitation. Not that that's what I did, I got formally married, but the lived experience of marriage doesn't have a whole lot to do with contractual obligation.
Indeed, even if you take it that marriage was somehow invented by "society" with no individuals involved, for "society" purposes, what people actually do with it remains up to them. And if an institution doesn't meet individual needs it will wither away. Individuals will use marriage for their own personal purposes, and claiming that society's will has moral force on their actions ("happiness is not and
should not be the only metric considered" my emphasis) is questionable. Even if there was a unitary "society", do people have a moral responsibility to do with their marriage what society wants, rather than what they want?
Don't get me wrong--I'm not a fan of pure atomized asocial individuality. I think society is important. But if a society is no good at helping people be happy and in love, then it's in need of reform.
As a side note, studies about single parenthood need to be very careful, and generally aren't because they're so often done by people who want a particular answer. It's true that children having a single parent correlates statistically with negative outcomes--but that's basically because single parents are mostly poor. Compare across equivalent income levels and the effects mostly disappear. So then it's in "society's"--or at least, the children's--interests for
either children to be raised by two (or more) people
or for society to help support single parents.