Ok so hear me out (sorry if this has been done :) )
Buttons takes Olivia to Mary's Widows Support Group
Olivia is obviously distraught about Karl, and Buttons has noticed. So he takes her to see the group and acts as translator.
He tells the story. The widows are confused but eventually just accept it. Olivia is a regular and valued member. The Widows appreciate her wit. She goes to all of their outings. Buttons always accompanies her to translate. The Widows help him with his grief over Karl.
There's even comic potential with Buttons not mentioning he knows Stede, and thinking Mary is referring to some other Stede if she ever mentions him. Buttons would 100% describe his job as High Moon Priest and Husband of the Sea or something like that. They're just peacefully co-existing. It takes a full year to realise they're talking about the same guy. After that they just shit-talk him (affectionately).