We told the MC that the A was the main issue right then and nothing else mattered ( chores? WTH???).
Our MC was well versed in infidelity and explained that until we had resolved every issue surrounding FWH's A then nothing else mattered.
We spent months focused on his A and the fallout.
If your MC is more comfortable talking about chore allocation they may not have a lot if experience or insight into this field. Trust me. If you don't have a great MC then it will take longer to resolve your resentments etc.
Maybe go alone and explain this to the MC and ask them to focus on the elephant in the room and not the dust circles surrounding it as you can dust once the elephant's dealt with and not before as that dust will just keep swirling around all the while that elephant is there