The center's research found that men between the ages of 31 and 50 are the most likely to have extramarital affairs. "Men of that age are relatively wealthy, and their mature personalities are attractive. After many years of marriage, they are also likely to have grown tired of the relationship," said Na Lixin, the director of the center.

Nearly 10,000 marriages end in China every day and statistics from the Ministry of Civil Affairs reveal a rapid rise in the divorce rate during the past decade. In 2012, 3.1 million couples got divorced, a rise of 133 percent from 2003.

Wang Xiuquan, a senior marriage lawyer at Beijing Chang'an Law Firm, said there is no available nationwide data detailing the number of extramarital affairs that prompted divorces, "but in the cases handled by my firm, extramarital affairs are definitely the most-cited cause, and account for more than 70 percent of all divorces."

The rising social status of women, who now have improved educational backgrounds and greater economic independence, has seen a sharp rise in the number of them having extramarital affairs.

Contrary to speculation that extramarital affairs invariably involve abandoned wives and "gold-digging" young women, sex is only one of the driving forces, according to Wang.

"When pursuing a partner, people often try to show their merits and may even pretend to be more caring than they really are, but usually their shortcomings are exposed after they get married. Trivial complaints, quarrels, a lack of attention and care on both sides, and the sometimes fraught relationship between mothers- and daughters-in-law are among the fundamental causes of failed marriages," he said.

Wang cited one instance where a man fell out of love with his wife of many years. The man had an affair with his secretary, which humiliated his wife, who worked for the same company. She proposed divorce and made a claim for the couple's property as compensation. However, when the husband fought the claim, and began investigating his wife's behavior, he discovered that she had also had affairs.

"For people like them in their 50s who have already fallen out of love, the earlier they get divorced, the more liberated and relaxed they feel," Wang said.

Unrealistic attitudes

According to Xu Li, vice-president of the dating network True Love Online, marital problems are a direct result of unrealistic attitudes and unwillingness to work to save a failing relationship. "Nowadays, people are too idealistic about marriage. If they find that it's not as perfect as they'd like it to be, they are tempted to end it as quickly as possible."

With the increasing social pressure, he said, more people emphasize quality of life, and have higher expectations of marriage. "This is not to say that people are treating marriage lightly; on the contrary, newlyweds pay more attention to the quality of their marriage life nowadays," he said.