The idea that it will always play out like that is ridiculous, and has little to do with polyamorous relationships. In order to be in a polyamorous relationship all parties have to know, thus what your talking about is actually just someone using a poor excuse for cheating on what was supposedly a monogamous relationship.

As someone who twice now has thought he had a second wife (relationships my wife and I had with women that each lasted about a year each) I just don't think this is really a huge issue. Mostly because relationships with more then 2 people living together is incredibly hard to maintain, and most people have little interest in doing so. It takes some severely non-jealous people, and most people just don't have the emotional architecture to do it.... as it isn't exactly like there is a guide book for atypical relationships of the sort... far from it.

When me and my wife had our last girlfriend, the one really big issue was immigration. Immigrating together as a married couple would have been easy, but our girlfriend would have had a much more difficult time. It turns out her alcoholism wreaked the relationship (she was not a happy drunk... far from it) before any of that mattered.

We're still looking for another partner... and if we find one I have no problems with getting a lawyer and making sure he/she has as many legal rights that marriage would grant drawn up as possible. I just don't know if society is set up for the logistics of this, and it seems like something that would have more interest from companies/organizations to exploit... then actual romantic relationships.

I feel for people who would like to have their decades long committed relationships involving more then 2 people legally recognized... I REALLY seriously do... but I just think the tiny fraction of humanity that would benefit isn't worth the complete rethinking of legal and judicial presidents that would have to happen first. Otherwise it would just be too easily exploited by people, likely more commonly then anything else.

Anyway. I hate the negativity associated with bigamy in general though. My wife is bisexual and would never feel a relationship with just a guy would satisfy her completely. Tons of modern liberal people think I'm really cool for accepting that, and not being jealous of her having a girlfriend. But be awesome enough to her girlfriends that they want to have a committed long term relationship with me as well... Instantly I'm a bad guy and objectify women or I'm just using them or something of the sort.... it's insanity. Maybe the guy that has a few girls following him around got in that position precisely because he DOESN'T objectify them.... doesn't that make more sense?