Fluttershy and Rarity's fantasies sound like they would make pretty fun stories of their own, I must say.

"But starting a about a month ago , and ending more recently when Spike and I… arranged our date… yes."

So the cure is to have a very special someone? Or otherwise be moving towards healthy sex*? Or just towards sex in general? Either way, I don't know why that would make Shining and Cadance uncomfortable. I wonder if they were trying to get samples for an experiment to see if some magic they sensed from Flurry was what they thought it was?
*By which I mean in marriage.

It would be more interesting than Twilight turning out to be correct at the end of the chapter.