Yes - like Ceoli mentioned above, these kind of things are pretty common. Also the source of a lot of the horror stories that prevent a lot of people from even attempting it. Kudos to you for at least trying ! Brave soul
A lot of this comes from "ignorance" and I certainly don't mean that in any negative way- but in the true sense of the word. A lot of people attempt things based on ideal & philosophical concepts. What most people aren't aware of - or maybe don't give sufficient weight to - is the difficulty & level of knowledge required to accomplish it. In the particular case of "poly" it's going to mean some deep digging into everyone's motivations and is going to force exposure of those - and any weaknesses & insecurities that we have. Some of these things we've pushed to the background and never been "forced" do deal with. Others will be things unique to a lifestyle like this and totally (or relatively) new. Things we've never really given much thought or study to.
Now some of this stuff has been forced to the surface. I think it's a wonderful thing personally. Knowledge of life and of OURSELVES is seldom a bad thing. Long term it's real helpful. How you three handle this "discovery" phase will impact everyone long into the future.
I guess I'd like to hope that having resources like many of the wonderful people here that HAVE been there, suffered the pains of discovery etc and come through them to something potentially better will serve as some small assurance that it IS possible.
But it means work. If everyone is willing - the rewards can be significant. If not, I hope you all walk away - not with condemnation - but with more knowledge and self awareness that will still have long term benefits. An experiment tried - and failed. Not because it's impossible - just maybe impossible for the particular individuals at that particular point in time/evolution.
Good luck. We're behind you to help any way we can. People here on the forum have a wealth of resources they can point you to for education & understanding and working through all the inevitable challenges.