I like that Kat was angry about being essentially ambushed when she thought she would be shopping with a trusted friend. First her trusted friend brings a guy she's never met along without telling her, then he crosses several lines and to top it all off he crosses a physical line. That really sets up her character to the player without stretching it out unnecesarrily. She's not some slut who jumps on the next cock as soon as she gets the excuse and instead has to ease into her husband's fetish.
On the other hand, it leads to speculation about her future. Maybe once she's into it she'll start playing along with stuff like this because "a real/superior man" can just "take what's his!" depending on choices made previously. Some of the teasers on here about stuff like denial and the humiliation choice already in the game could be hinting at stuff like it.
I also like how Lucie owned up to it instead of doubling down on her fetish. Making sure her friend was alright afterwards and taking action.