Bluebird, I think moving in together is a monumental undertaking, especially if you are in the early stages (first few years) of your poly relationship together. I'll tell you what really put the whammy on me, is the layout of the house. It was a great layout for people with a comfortably worked-out dynamic together, but it was a terrible layout for people just now attempting polyamory for the first time in their lives.
The killer for me was the lack of an attached bath for my bedroom. This severely undermined my sense of privacy. It meant I did not have a cave I could bury myself in during my times of turmoil. I was going to be forced to walk past the living room every time Nature called. These trips I made back and forth to the bathroom punctuated the fact that I wasn't quickly warming up to Brother-Husband's company. For me that was normal; for him that was a sign of rejection. He felt like I was rejecting him. Whereas from my viewpoint I just needed more time alone before I'd be ready for a lot of socialization. Brother-Husband and I were raised in two different worlds. The difference in how we were raised affected how we perceived even the little things, and those little things were killing our rapport with each other.
The next problem was that I did not see myself as a primary partner, and that I did see myself as being vulnerable to the "law of veto" should Brother-Husband choose to invoke it. In official terms, our V had no secondaries and there were no veto powers. Hell if Snowbunny had been forced to choose him or me, I'd have probably "won" that contest. But that's not how I felt. I felt like my position in the family was very uncertain.
Now add to that the fact that Brother-Husband was just newly getting acquainted with the concept of his wife having sex with another man. He was trying but I don't think it was easy for him. At the time I definitely didn't think it was easy for him; in fact I suspected that he was not succeeding. This suspicion was reinforced when Snowbunny and I were alone together in my bedroom, and Brother-Husband was out there, frequently walking right past the bedroom door, making lots of extra noise compared to the usual, lots of noise in the kitchen etc.
No doubt some of this was exaggerated perception on my part, as I was afraid he was mad about me "sexing his wife" and as a result confirmation bias raised its ugly head in my mind and well, I gotta tell you, it ruined much of the mood for me and sometimes it ruined all of it. Which was a disaster because back in those early days I desperately craved sex and was reduced to a pile of bitter wreckage whenever a planned/promised sexual encounter fell through.
All of these factors piled up and increasingly aggravated each other until the only solution was to get Brother-Husband and me out of the same house. It became necessary for me to have a place of my own, a cave I could absolutely retreat to that was totally, securely out of the range of Brother-Husband's sight and hearing. So, he and Snowbunny moved into a townhouse in Albuquerque, and shortly thereafter I moved into a small condo unit about a ten-minute drive away. The drawback was that Snowbunny had to drive back and forth to spend time with her two men. The benefit was that it saved our endangered V relationship. It didn't save it instantly. A long spell (a year or two) of detoxification had to go by before I was really ready to start living in the same house as Brother-Husband again.
And even then, everyone now understood that Kevin's bedroom absolutely needs a connected bath at all times. In order for me to feel comfortable about "hanging out" with Brother-Husband, I had to know that I had a completely autonomous space I could retreat to if and whenever my own feelings got out of control.
Of course as you can see from my above post
, I have many personal problems that the average guy doesn't have. So there are things I would need that the average guy wouldn't need.
But even taking that into account, I would still strongly caution anyone who is about to move in together. Maybe I wouldn't say, "Don't do it, it's impossible," but I would say, "Be really careful, there's a lot of things that can go wrong -- and establish privacy like nobody's business in the beginning." Needless to say, I'm an avid advocate for connected baths. They do wonders in the way of creating "cave suites" into which a person can hide when things get really tense, awkward, and/or plain old bad.
I can tell you more about the early struggles our V had, but those are the main things that come to my mind for the moment. Questions about specific details may ferret out more of my memories, memories perhaps that would be especially useful to you.
In general though, I just think it's hard for almost all poly units when they first get together. Lots of jealousy and insecurity. Lots of fears and frustrations. It takes people a long time to learn each other's quirks and idiosyncracies, and that learning is necessary before people can figure out how to live comfortably together.
I once heard the maxim, "First year forming, second year storming, third year norming." I wouldn't call that a scientific formula you can plan on, but it does express the general idea that, "Hey, you are going to have some rough times together. You have to prepare yourself for that, and don't beat yourself up when it happens. You're not failing, you're just going through a natural part of the process together."
I hope this post serves as a starter for you to prepare for your year of storming -- and maybe it won't be a year; who knows what it'll be. Just know that it's hard for people to get to know each other when they're just starting out on a poly venture together.
And know that, as my case demonstrated, each individual will have very different and unique needs compared to each other individual.