The first law office I worked in, the managing partner's (he owned like 60% of the firm) wife had an inordinate amount of control. Eventually, his two junior partners had had enough and left and convinced me and the other associate to leave with them. We all became partners at the new firm and our first (and foremost) rule was NO WIVES (this turned into NO SPOUSES when we added a female partner). Wives were allowed 0 say in how we ran our business. Now, my wife (and I'm sure the other spouses) would try to influence me, but when it came time to vote, her only sway would be through my vote, but she didn't really have a say. It pissed her off, but it made for an easier time running the business.

A lot of times, I've seen doctors who cheat on their wives with someone in their office. This results in the wife becoming the "office manager" more so she can keep an eye on her wayward spouse than anything else, but eventually devolves into the wife taking too much control over the business.