I am NOT finger pointing, or blaming. I am merely pointing out that there is an added dimension to a SSM when the wife is HD. Because we, as women, are brought up to believe one thing and then that turns out to be untrue in our personal relationship. I cannot emphasize enough how much of a mindf*ck this is. This element is not present in an SSM where the male is the HD partner.
So in that sense it most certainly IS a special circumstance.
Not that it makes any difference in the long run, or in how you go about solving the problem, just that it takes a whole other set of mental attributes to deal with this other dimension.