People often end up dating, and loving, and marrying someone in the exact same line of work. Maybe it's because office trysts bloom into real romance, or because we end up attracted to people who share our passions (and according to at least one study, our facial structures). But shacking up with a "work-linked" partner has some costs, according to new research.

Professor Gail Kinman of the University of Bedfordshire co-habits with a similarly employed mate, something that's particularly common in academia. Kinman read that in the U.S. 40 percent of academics live with or are married to another academic.

Luck would have it that Kinman had an extensive database of U.K. academic employees and their partners from her research on work-life balance at universities. So she scanned the data, and found that 45 percent of those in her sample were romantically involved with others who worked in academia.

She compared 291 academics with "work-linked" partners to 350 academics with partners in separate industries, and found that the professors who lived with another professor had much poorer work-life balance, labored for more hours a day, and had much greater commitment to their jobs. She presented these findings on Thursday at the annual conference of the British Psychological Society Division of Occupational Psychology.

"The blurred boundary means that job demands were more likely to spill over into the home setting," Kinman told AOL Jobs, "because they would talk about them more often."

"And these people would socialize with people who are academics," she added. "There's no real kind of recovery time away from the job."

Competition may have a role too. "Obviously, if your partner has a success, they were very pleased. But there may be a little bit of a jealousy, a little bit competition."

Kinman followed up this study with 32 online interviews with academics who had "work-linked" partners, to give her findings some qualitative meat. Turns out, there are also great benefits to having a partner with the same profession.

"If you live with somebody who does a similar type of job to you, they're more likely to have a better understanding of what you're going through," Kinman says.

Interestingly, participants across the board said that their partners had a better work-life balance than themselves, and also thought that they were more understanding of their partners' issues than their partners were of theirs. Of course, this attitude is probably true for anyone in a relationship.

Kinman realizes that her findings have limited relevance to people who aren't academics, since professors have an exceptional level of control and flexibility when it comes to their work. She plans to examine the same questions in other jobs, particularly police officers, who also live together at above average rates.

These results don't mean that people should avoid dating people in their field, if that were possible anyway. Rather, Kinman's advice is similar to what any relationship counselor would say to any couple about pretty much any problem: Be clear about your expectations, and communicate.