That's not really how loyalty to your homeland works... If you were loyal in the first place, it doesn't disappear so easily with the death of one person, no matter how dear to you he was and how treacherous the current ruler is. And Aideen here doesn't simply want to carry out a coup d'etat, she wants to erase her homeland from the map. Nope, I don't buy it, dear author.
In other words, it's hard for me to sympathize with someone who is ready to discard a whole nation for a personal grudge. It could be more palatable if at least she was shown thinking a lot about why Jeldion was a much better place to live in than Perdi and why there would be no discrimination against her compatriots despite the long history of enmity between the two countries.
But so far, Aideen only thinks about herself and the few people close to her, even though she is a potential heir to the throne, not some peasant or craftsman with no particular concern for politics and no clear understanding of international relations. For God's sake, she is directly asked "but what about the innocent civilians", and all she has to offer in response is "I'll try to avoid too much bloodshed", with no further discussion of the matter. What a disappointment.
Be honest, girl, the country your father loved didn't disappear, you just needed an excuse to betray it because it'll make life easier for you. After all, it's one thing to rely on a foreign power to help it conquer its long-time adversary, and quite another to become the leader of the anti-emperor faction and accomplish a coup without destabilizing your country in the process and also without triggering an invasion by Jeldion because of Perdi's perceived weakness.