For every crazy thought that has ever passed through my head, there's a headline about someone from Florida doing that exact thing, except taking it to another level.
Have wondered if there is an economically and romantically viable successor to modern marriage.
I can tell you as a participant in a two person marriage that I'm not sure it would work for me, but can imagine the benefits.
That could just as well be evidence for formal marriage not being easily sustainable.
A formal marriage comes with its own pros and cons compared to other relationship types, as such I don't think you can use divorce numbers as evidence for intimate relationships being difficult in general.
The rise in divorce rates and the decrease in marriages could just as well be interpreted as formal marriage being perceived as too difficult of a relationship type to sustain, so people are increasingly opting for alternative types instead.
They're not the Alpha and Omega on the matter, but it clearly shows that A- The people were attempting to create and sustain a long term romantic relationship and B- They were unable to do so for some reasons.
It could be a correlation and not causation thing as well though. I think it's difficult to provide anything truly concrete showing that intimate relationships are difficult to maintain using statistics. Much like the original article, there's just far too many moving parts (cultural expectations, communication skills differences, personal traumas, trust building, etc) that play into the equation.
With that comes a ton of expectations and pressure, internally inside the relationship, and externally from society.
These are not present to the same degree with less formal relationships because the stakes are generally considered not as high because there's no formal divorce to go through if it shouldn't work out.
Thus married couples might be more likely to suffer from "performance anxiety" in their relationship compared to less formal relationships.
Different values/desires will always be an issue, but if two people can agree on those, why shouldn't three people be able to? The only reason some are so opposed to this idea is due to old religious stigma enforcing the idea that we have to be monogamous no matter what.
As for the last question: because the more people you add the more mutually incompatible desires are in the picture.
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)
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.
You can, but it is not wise.
The Federal government gave them hell about it, going so far as to seize any assets of the LDS church. Utah wouldn't have been granted statehood if they hadn't condemned it.