I think it was one of those times where it's a specific slang phrase in a language that you can't really translate it directly. I just assume it's similar to the american slang "butt buddy" as in they are in a gay friends with benefits situation.
I've only read this through some yt channel named cutie ringo joy or smth, and read till some 65th chapter i dont remember. I dropped it like when the author went on a hiatus and then i was broke
That's gonna be my new catchphrase!
....i mean the husband is triggered lmao i like it