@tblst
that bubble alone says she won't use it BUT it is a part of the longer sentence where she lists restrictions or rules of using her power. It may sound like a rule she made for herself so "won't" is not wrong BUT but if you look at the part where the narrator explains what she really wants, it becomes clear that using her power on someone she likes would get in the way of obtaining her "true love" hence "can't".
BUT again there are a lot of cases where they use the simple negative instead of potential negative to say they won't do something because they cant, as in "I don't drink" (because I am a minor)
@Xxjuggernaut To be precise, she considers that anyone could be her prince, so she treats them all equally and nicely just in case she finds true love among them. It's pretty evident that Elizabetta yearns for a stable, monogamous relationship rather than a harem she can easily get. Since her powers make it difficult for her to tell what is real love and what is fake, it is reasonable for her to yearn for the real deal.
so does Elizabetta love Lied-kun in a serious way? He fell in love with her without her needing to use her powers on him and she noticed this, making him the guy she had been yearning for but Idk if I'm wrong in this.