Thanks so much for sharing your process with us. Your honesty and vulnerabiltiy with the group is inspiring.
I wanted to share something from my personal experience. This was not a poly relationship, but I think this concept would help anyone wanting to live together- poly or not.
Anyway.....After dating for 18 months, my female partner and I decided to move in together. We were already in therapy- not because we were having problems, but because we wanted a professional opinion about our relationship.
We did live together for 12 years and had a very functional relationship and one of the advantages we had was a result of something our therapist suggested and we took it seriously.
It echos what others have already said:
We each had our own personal space within the house. The personal space was considered sacred and we each gave special attention to turning our individual spaces into something that was special for each of us.
The agreement was that a closed door was considered normal and healthy. An open door did not mean that someone could freely enter, however. But we would invite each other into our spaces. When I was in her space, I would consider it a special privilege and would act accordingly. She would do the same in my space.
Therefore, we would make dates and wait to be invited into each other's spaces. It kept things really special for us!
My best wishes to all 4 of you!!