They say (oh, those mysterious "they" of English language conventions - they do talk a lot), that there is nothing more expensive than a free advice. I believe so too. It's impossible to provide good advices without looking into particularities of each case, and nobody would do that for free. That's why within these free-for-all posts I usually go with sharing of knowledge; if it's appropriate - with suggestions; and only if a statement can be safely generalized, I call it an advice.
With that in mind, I am confidently offering the following as a friendly advice: never say that you "wrote the book on" whatever it is you think you know through and through. It's never true. None of these proverbial books of expert knowledge are ever finished. Just when you think that you can close it and send it to the printers, there is a need to insert a new blank page and relate a freshly unique, never before experienced tale.
One of such areas of expertise for me deals with typical characteristics and behavioral quirks of the entrepreneurial executives - those to whom I simply refer as "bosses." My career allowed me to observe many of them in different situations - as my employers, clients, business and social relations, even charity connections. I honestly thought that, based on this experience, I can predict the behavioral patterns of most business owners, including those sharing power and governance as partners.
Alas, my anthropological study of bosses did have a gaping hole, which I would have never discovered if my life didn't expose me to peculiar antics of a married couple as business partners. As it turned out, all regular characteristics of executive co-existence described in my previous post "The Servant of Two Masters" still apply, but with some very specific aggravating additions.
No matter how hard they try to keep it professional, they can never completely eliminate marital undertones. While they usually manage to control the urges of affection, it becomes more difficult for them to rise above the intimate knowledge of each others' weaknesses when conflicts flare up. I am not necessarily talking about full-blown battles of Lucy-and-Desi magnitude with hammer injuries. But take my word for it - witnessing spousal tiffs and spats cause extreme discomfort; to the point that members of the executive board wish they were Hogwarts graduates with apparition licenses. You just want to disappear.
One of my biggest complains about dealing with multiple owners always was that, unless you get them all in the same room, you must work with an assumption that what you explained to one is unknown to another. You will need to repeat everything to each partner individually. Well, don't assume that the situation is different just because the execs belong to the same household. It's even more unlikely that they will share your info at home.
And then there are those very special casual dismissals husbands and wives reserve for each other - shrugging-offs and waving-offs, which are frequently more harmful to one's ego than verbalized insults. The shit gets especially intense when the issues of personal value to the business or equitable compensation come up.
All you can do is to pretend that you have gone momentarily blind, deaf, and inattentive - didn't see, hear, or notice anything. More importantly, don't take sides: eventually your allegiance will be discussed at their kitchen table, or in bed, and both of them will hate you.