> By the time you're making decisions like buying a house or having children you cannot treat the relationship that informally anyway. You can still treat it l

> By the time you're making decisions like buying a house or having children you cannot treat the relationship that informally anyway. You can still treat it less formally than if it'd be an actual formalized relationship. A lot of this boils down to societal expectations and norms which are not set in stone, but rather constantly evolving. The nuclear family, with their own house and dog, used to be ideal but at this point, it's a pretty outdated ideal that doesn't work with current economics, thus alternatives might be more viable. I'm also not convinced that adding more people to a relationship inevitably will make it more difficult no matter what. People are way too individual for that to universally hold true and there's plenty of historical and modern examples of non-monogamous relationships as counter-examples. > If there's nothing but religious stigma at work, why aren't the Mormons still polygamists? (there are exceptions but I think we can round them off for the purposes of this discussion Because afaik there are still US states with laws banning polygamy? These are societal norms in large parts formed based on religious dogma, they ain't some "natural law" that can't be broken or changed, just like the nuclear family ain't necessarily the ultimate smallest societal unit.