11. What changed the relationship between Margeurite and her husband?

This kind of depends where in the story you are referring to. I think the major change happens when Lady Blakeney takes the opportunity of Percy's absence to peak into his study, which is organized and neat. She wonders why Percy presents the image of the buffoon, when he is clearly a competent and thoughtful man. She sees a small gold ring on the carpet, which she picks up. It has a flat shield, engraved with a scarlet pimpernel. Lady Blakeney suddenly realizes the true identity of her husband. This is when her relationship with Percy really changes.