This is not exactly my situation but my husband and I have some differences of opinion that we are working through, and I found the latest episode (16) of the podcast Pedestrian Polyamory to be helpful in tackling it from a new angle.
http://www.lifeontheswingset.com/category/pp-hub/
Basically, he's set a rule (must be a triad) because he sees it as a solution to a problem. But it's probably not the only solution, and he needs to figure out exactly what the problem is that he's trying to solve so you can think of other options.