I think the key issue is the "meddlesome" bit rather than the relationship with the sensei. If you approached the problems you have with the spouse with the same intent that you would with anyone else in the dojo, effectively disregarding the personal ties, then if she plays the spouse card this would give you the initiative (and provide you with a valid, demonstrable grievance). At the moment, you could still be accused of just incorrect perception over the relationships effect in the dojo - I said could, not saying you are.
Having said this, I know a lot of people find it hard to be objective about their loved ones, so I'd suggest excessive diplomacy to start with. However, if all else fails, find another dojo. Just glad I've never had to deal with this problem in my sensei, just in some "dojo couples".