By Chen Hong

SHENZHEN: Gao Chen is typical of a growing trend - she is educated, successful and married to a husband who has a mistress.

"He comes back home once a week and I know he has a lover out there," Gao said.

The couple has lived in this southern boomtown for more than a decade, climbing from poor university graduates to successful business people running a big furniture company.

The two had a tough life when the business started but they loved and supported each other, Gao said.

However, when they bought a villa and luxury cars, their relationship changed.

According to the city's government-financed support center that targets rising mental health problems in Shenzhen, about one-fifth of its calls are about extramarital affairs - making it the No 1 emotional problem.

Figures from Kang Le Yuan psychological consultancy, one of the city's largest organizations for marital relations, showed that about 80 percent of the 6,000 cases it handled last year involved extramarital affairs.

The rise in affairs is also causing a boom for private detectives.

A decade ago, detective Zheng Fan handled one or two extramarital affairs every month.

Now he receives at least six calls and five e-mails every day.

The number of such companies, which mainly work on extramarital investigations, has also blossomed to more than 200 from less than 10 a decade ago.

Zheng said people's attitudes toward extramarital affairs have changed.

"Men used to hide their lovers, but now their relations are open Even the security guards know who has a 'second wife'," he said.

Meanwhile, more of the lovers believe it is not wrong to be with a man who claims he no longer loves his wife, he said.

The private detective, who now positions himself as a "doctor to extramarital affairs", said a majority of the men with a "second wife" have good educational backgrounds, considerable incomes and have been living in the city for a couple of years.

They felt spiritually empty while becoming successful and rich and intended to re-experience the passion of love, Zheng said.

Businessmen, public servants, and banking and IT workers top the list.

On the other hand, most of the "second wives" who were born in the 1980s are said to have a strong desire for material goods.

Only some of the women were motivated by love, Zheng said.