When I moved to Stonyfield Farm in the mid-1980s to live with my then-fiancé, Gary, I immediately went to work in his yogurt business. I worked part time in the office and in sales, reporting to Gary, and part time as a yogurtmaker. At that time, the "factory" consisted of some jury-rigged machines in our barn; turning out good product required improvisation and luck. But my sales job was just as taxing, in personal ways I hadn't anticipated.

I started working for Gary for the same reasons most spouses get swept into entrepreneurial ventures: I was available, capable, and cheap. My role grew out of expediency, not because I possessed any particular skills or an abiding passion for the job. Because my future depended on the company's success, I was certainly dedicated. But Gary and I were not equal partners living a dream of our joint creation. And so we suffered double the stress without enjoying double the personal fulfillment.

Many couples meet on the job, and office anxiety follows them home. But when one spouse goes to work in the other's company, there is no relief in railing against the boss or fantasizing about going elsewhere. Even when one spouse doesn't report to the other, the entrepreneur usually wields implicit authority--not ideal when you're trying to sustain a marriage of equals. The work environment may reveal quirks or irritating habits in both of you that never surfaced in domestic life. The most routine operations can generate a dozen new issues a day on which you disagree. And home ceases to be a sanctuary when dinner-table conversation picks up where the afternoon huddle left off.

Even the way you talk to each other is affected. Michael McMillan, an Inc. reader who works with his wife at their family-owned call center, Answer Center America, described it to me this way: "Problems at work demand yes-or-no solutions, and there's often no time for explanations. You need to keep emotions hidden at the office--you can't personalize disagreements." At home, of course, conversation, compromise, and nuances are important. Everything is personal. Making the shift, from tough and impervious at the office to communicative, open, and sensitive at home, can be challenging for both spouses.

For Gary and me, working together revealed aspects of our personalities that had not emerged in two years of courting. Often when he'd give me instructions on how to handle our clients or suggest travel shortcuts for business trips, he'd talk fast and skip details. He sometimes became impatient with my confusion. For my part, I personalized everything and felt hurt by his occasional abruptness. I was unable to compartmentalize--a critical skill for couples who work together. Unrealistically, I expected that we'd take the time, even during the workday, to solve problems as they arose.