Re: High level power abuse
I made my suggestion based on Frank's statement that he observed the behavior in the dojo. If the instructor and the student are adults and want to have an affair, that's their business. If they use the dojo to facilitate the affair, then it becomes dojo business.
And note that I advised Frank to speak with his teacher privately, and to speak with the other student only if he had some kind of already-existing relationship with her.
And I agree with you, Neil: throwing around terms like "un-aiki" is not helpful.