If nothing else, if you just want it to be clear that "there's nothing more here", having it just loop the one scene, rather than sometimes doing the scene and then sometimes not, would possibly help? Since, for most other relationships, brainwashings, etc., when you hit the terminus point it's either revisiting one last scene, or talking to the person doesn't get you a scene and instead you have a couple that spring up randomly, like the Charm version of Sonya's thing, where it's sometimes when you enter the zone, and sometimes when you fast travel for other variants, and so on. The simple fact that there was two interactions, one of which where nothing seemed to happen other than getting the pink eyes for a bit, and the normal scene, probably also contributed to me idea that there had to be something else there, because otherwise what were those false starts about (according to my internal logic)?
... And failing that, could always add it to the H-Scene collection doc, so people who are braining at it and can't figure out what to do next can look it up and go "Oh, there isn't anything to do next."
See also: Me and... Kye? I think? The werewolf guy on the building roof who insists werewolf girls should be bimbos, but doesn't seem to get a scene variant if you actually are a bimbo. Or maybe he does and there's some further requirements to it? Dunno! I'm sure you've been inundated, over time, with people reading too much into "Oh hey, character made reference to (whatever) mind/fetish state that exists in the game" then responding to it with: "I should go get it and come back!" when that was more supposed to be in scene fetishization than hints/instructions. Can't write every possible iteration/interaction angle or you'll drown in the authorial work, after all.