She actually is nice, she was just interacting with them normally like we're used to, but because they're very conservative they saw it as flirting. The asshole prince and his followers didn't tell her this and whenever the girls tried to tell her the asshole prince would yell at them since he doesn't want anyone else talking to her. Personally I think those jerks enjoyed the "flirting" and that's why they didn't tell her anything ( ̄へ ̄)
After she finds out that she isn't the Saint she doesn't really know what to do with herself. She also wish to be acknowledged as being of use for the kingdom (the king said something along the line of Sei having proven herself which made her feel out of place). She graduates school and Sei recommends her to try and work for the magic division since she can use quite a few types of magic.
i hope the other saint and prince kyle are suffering..
thank u ლ(´ڡ`ლ)