Do or die!
Not really. I'm just kidding with you. ;)
After the comment by anonymous in the previous post, I realized that polyfidelitous relationships are something that I haven't examined previously. For me, starting out with an LDR for many years, polyfi wasn't terribly practical. The physically separate nature of that relationship for many months at a time didn't lend itself well to sexual or emotional exclusivity, even with more than one person. So, let's go take a peek at an option that I passed up years ago, not considering it feasible at the time.
There's a broad spectrum of relationship styles that exemplify the term "polyamory". On one end of the scale, we have people whose relationships are more compartmentalized, sexually and emotionally unregulated, "free agent poly". On the other end of that range you'll find polyfi. Some have referred to it as "mono plus one", as the most frequently observed configuration is three people, typically a couple that has absorbed a third person, who have agreed to be sexually and emotionally exclusive within that triad. Mono plus one is often said in a disparaging manner.
For me, it's simply another choice available to those of us looking at relationships that fall outside the norms. One of the main concerns that people often have about poly relationships is how to keep things simple, stable and safe. While polyfi certainly doesn't guarantee any of those things, it can be a way to manage worries about uncomfortable complexity in wider networks.
I've seen more polyfi folks with school age children. I may be drawing an erroneous connection here, but I can see where someone may hypothesize that polyfi would likely produce a higher level of predictability and family stability. That can seem very attractive to a parent that wants to protect their child(ren) from experiencing shifts in family composition on a semi-regular basis.
Another oft touted reason for choosing polyfi is to minimize STI risks by keeping the number of people that are "in the pool" very limited. I have no clue if there is any actual statistical data to back the effectiveness of this idea up, but understand the logic of the idea. An off-shoot of this is to assure that any children conceived are the biological issue of the family members.
Detractors of polyfi have said that it contains a level of ownership and control of one's partner(s) that is undesirable, that the 3rd partner brought in is seldom an "equal" in the dynamic with the pre-existing couple, or that they are actively hostile to those of us with less structured poly models. To my way of thinking, it's really only the last one that concerns me directly. The first two are good partner selection criteria that those opting into a polyfi situation should be aware of and screen for to the level of their comfort.
For those who think that their way of doing poly is the OTW (One True Way), I'd encourage an examination of the issues this has caused within religious communities throughout history. We all have our path to follow, and sometimes, we may even switch camps. The thing I think we can all get behind is supporting informed, consensual, healthy relationships, regardless of the configuration they are executed within.