It's a bit unique in that you are also an applicant/recruit to a sister institution. My wife is in the private sector and when I applied, it had zero impact. Frankly, it isn't the job of medical schools to accommodate their decision process because you're married. That being said, I have found at my school that they are very supporting of spouses. I speak on a panel for students and spouses and always mention that one of you will be getting an MD, but both of you are going through med school.
But to you question, I don't think it's in poor taste for you to tell your boss that your acceptance of the position is predicated by your spouses acceptance into the med school. If they decide to try and pull rank/leverage, go for it.