Funnily enough the "only women suffer enough to be magical" is a trope I've seen in a few stories. Especially bad fanfiction. It's always stupid, but it tells you a lot about the author's mindset. It's the kind of mindset that gets you ideas like "women are the real victims of men dying in wars."
In this case, the man sitting beside both of them is basically a slave, and has already essentially reached the highest status he'll ever have given his birth, and the obvious author insert sorceress is preaching about "all men just make rules". It's so hilariously out of touch with the characters around it that it really feels like the author just wanted to preach some misandry through their worldbuilding. There are stories that I like with female-only magic... they don't try to explain it with a bad tumblr blog post masquerading as character dialogue.
This exposition dump is a really bad author-induced blemish that detracts immensely from an otherwise decent story. Honestly... I'm thinking the entire sorceress character should have been scrapped. It's starting to feel like the author's self insert narration dump side character is sucking up all of Eris' own agency in the story.