Sounds like you want to be in a CLOSED "V" shape thing with you as the hinge person.
Sounds like at this time, you are NOT open to an "N" shape thing where your BF and you BOTH have another sweetie so BOTH of you are shared hinge people.
If you are not up for it, just say so honestly.
It is not about "fairness" like other people are cookies. You have one so... he gets one. It is about what you are willing to be in and can do WELL. If you are not willing, do not play in that shape. Better to be CLEAR about your wants, needs, and limits.
If you do not want to? Say so.
If you need to settle in here to THIS new normal first before contemplating other stuff? Say so.
If it is a soft limit, that could change over time say so.
If it is a hard limit, that will NEVER change, say so.
If it is an unknown limit, but still a limit, say so.
You sound like you are just getting used to a 3 people polymath configuration. Adding another player is changing up the polymath
and changing the number of "mini relationships" inside the greater polyship.
I sure as heck would not want that right away. Stress is enough one bit at a time! It does not seem "fair" to my health to be piling on more crazy stress. A new person in the family ranks a 39 on the stress scale.
It may seem like just (BF 1 + Other) and only 39 hit points for stress.
But wait... Other has to get along with
- Other <---> Other (If they are in your polyship, now you have to deal with how well they know themselves and how honest they are with themselves because they are part of your world now.)
- Other <--> You (Communication arrow = Do they communicate well with you? You to them?)
- Other <--> (You + BF1)
- Other <-->(You + BF2)
- Other <--> BF1
- Other <-->(BF1+ You)
- Other <-->(BF1 + BF2)
- Other <-->BF 2
- Other <--> (BF2 + you)
- Other <-->(BF2 + BF1)
- Other <---> (You + BF 1 + BF2)
- (You + BF 1 + BF 2 + Other) <--- the whole polyship gang here working as a team
"Other" does not have to be everyone's lover. Does not even have to be everyone's friend. But does Other GET ALONG decently with the other people in this polyship? Basic friendly and polite?
Even when making the repeat layer ones grey so they do not count? That's 9 mini relationships inside the potentiual 4 person polyship with "Other" in it. There are other mini relationships inside the bigger polyship that do not have Other in it. (You to yourself, you to BF1 alone, etc)
But just those where OTHER does appear? Nine. 9 x 39 stress hit points? Welcome to the land of 351 potential points if ALL those tiers are wobbly. Yay. Welcome the polyship health to the land of stress induced illness!
Now that's a worst case scenario. The ideal would be NO problems at all. 0 stress hit points. The reality is somewhere in between that range 0-351. Your polyship could work to reduce stress so that the polyship can take on the weight of adding a new player.
You are there, you know what your reality is and what the actual stress number could be if you ask your people where they stand and how they feel about it. You guys determine what you can afford to pay for the price of admission if you choose to Open again to include another player.
351 potentional risk points is enough of a price tag to take a pause to reflect and think it out REALLY WELL before going there. It can be done. But make sure ALL your players are fit for it and up for it.
WHAT are we taking on? Are we fit enough to go there?
WHEN could we go there to minimize stress?
HOW could we go there to minimize stress?
Everyone is responsible for their own well being.