Oh, I’m not saying I would do it- just that I would not commit to such a job in the first place. It is completely unethical to give your word to something and then break that word- especially in this case, since the principal did not want to hire her and only did at the insistence of the girl that she would not leave.
The other solution- which, by the way, a friend of mine put into practice- is to remain in that city until you complete the school year. My friend married a boy who was learning in Monsey, but they found an apartment near where she was teaching so she would be able to complete her achrayus to her employer and her students. I was very impressed with her-and her husband for being a mentsch.