You could say I am in the position of B as I am the hinge in a poly-V. I cohabitate with wife Bird, and girlfriend Daisy.
Most of our time is spent together, however I think everyone having a personal space in the home has been essential. I know you are not shopping for a different home, but have you considered it? A condo an hour away is not the same as having a personal space in the home, however if B says he can handle it I do not see any reason not to believe him. On the other hand, its not a bad time to buy a different home if you are in the position to do so… What about relocating your home closer to B? Between you and B there are three properties, consolidation or relocation of those assets seems possible… Why cram into a single property when you have the means to own multiple?
Our poly-v began cohabitating mostly for financial reasons. We considered having separate properties close to one another however we found (in the city where we live) that we would pay close to half the cost per square foot of living space by consolidating into one large home instead of purchasing two smaller homes.
Setting-up “rules for private time/family time/alone time” is as simple as having a conversation, if you are worried about it you can ask to create a schedule. Our Poly-V had a schedule for a while, but it was not working for me, so we did away with it. I do not know what the difference is between “alone time” and “private time”, but for the purpose of my post I will assume private time means sex and alone time means… Watching a movie together? Maybe you could clarify?
I think it is important that whoever wants alone time or private time with B can go off and do so without asking the third to seclude themselves to their room. For example, our home is three tiered; Daisy has a studio space on the lower level, and Bird has the master suit on the top level. Daisy and I can spend alone time in the studio and Bird can have run of the house or an entire level of separation if she pleases, and vice versa. We have entertainment set up in the studio, main level, and master and while we are usually all enjoying each other’s company on the main level we have the ability to seclude ourselves to either the studio or master for alone time, like watching movies, talking, cuddling, ect..
I bring this up because separation available in the home helps with privacy and noise levels. I know open concepts are extremely popular however that type of design creates privacy and sound transmittance issues. You might want to think about how the bedrooms are situated and how you feel about possibly hearing B and your meta having sex, especially in an open concept as noise can transmit to a large portion of the home. My bedroom is right next to the master, so it does not tend to be a location for sex as Daisy’s studio or Brid’s master are far apart and maximize privacy. I still maintain my own bedroom and a second room as an office so that I have my own personal space as well.
More to think about: I live in the USA and some of this may or may not be applicable to you, however it might be worth looking into whether similar laws and restrictions apply to you.
1. Some US States have common law marriage and cohabitation laws intermingled. Your poly-V cohabitation could potentially violate bigamy laws. Consider getting legal advice on how to navigate that complexity (if it exists in your State)
2. Some cities have ordinances in place regarding how many non-related individuals can live in a single-family home. You probably will not be in violation at this point, but if more people move into the home you should make sure you are not in violation.
4. Homeowners associations. Some HOAs also have rules that govern how many non-related individuals can live in a home under the HOA jurisdiction.
3. Responsibilities for home upkeep and finances… It can get really complicated. As the homeowner, is B solely responsible for the cost of maintenance? Will you, or your meta be asked to throw in on a new roof on a home you have no ownership of? Rent? Bills? Upkeep compensation? This topic is deep. And in my experience, the longer we poly-cohabitate the more our finances have become intertwined, it is an ongoing never-ending discussion. You may want to consider creating a legal cohabitation agreement with an attorney.