I think the reason the age gap feels less...uncomfortable...than it usually does is the nurse never really exerts any of her authority. There's always the inherent power dynamic issues between an adult and a child, but at least in this case, it's not as important as if she were her actual teacher or boss.
It's still a little weird though. How old is the nurse, even?
All this talk me made me realize, did we ever actually see what the system would've rewarded yvonne with if she had done what it wanted? What were the points actually worth?
Another story with the same start but a fun sort of twist is May I Ask You One Final Thing? Which is not Yuri, but it turns out the scorned woman is kind of a fight-crazy girl who proceeds to punch out everyone at the party where she's rejected, and then goes on to join a different prince in cleaning out the kingdom of all the people who supported her ex-fiance.