One gripe I have is how little screentime Misona or whatever her name is gets. If the prince was just going to lose interest, why not show their relationship becoming strained? It's all very wishy-washy, but I suppose this series is about the fluff.
I mean the baron would have to be extremely stupid to sell her out. You get an extremely powerful mage with ties to spirit kings to help keep your town safe. Especially after her putting up a barrier, it'd be better to let her stay