condom only forever vs going fluid bonded with one reg play partner — talk me thru it

F38 H40, in the LS abt 4 yrs, condom only with everyone outside our marriage no exceptions. we have one couple we've been playing with for like 14 months now, exclusive arrangement on their end too (they say), all four of us test q3mo and share. she brought up the idea last weekend after wine of like... maybe we've earned going bare among the 4 of us. dh is open to it. im the holdout. it's not that i don't trust them it's that i don't trust the CONCEPT of trust in this space, ya know? has anyone here gone fluid bonded with another couple and how did u set it up without it blowing up later. and what happens when one couple wants to play outside the quad, do u just renegotiate every time omg my head hurts