All marriages go through turbulent times, and those that last apparently have two common pillars: commitment and clear expectations.

Lin Tianfu's black-and-white photo series Love of Half a Century captures the love and devotion of 200 elderly couples from all but one of China's 56 ethnic groups. Each photo comes with a short summary of their love stories. [Photo/Provided to China Daily]

These couples unceasingly work on their problems because divorce to them is "not a consideration", says Regina Ho, a family and relationship counselor with Oasis International Hospital in Beijing. They understand marriage, she says, as a life-long commitment.

At the same time, they have fewer blowups because expectations are clear. For instance, wives accept that husbands need their boys' nights out (as opposed to spending every evening with the family) and that a spouse comes with in-laws (so you try to get along with them rather than constantly complain).

"My feeling is that people today are more dissatisfied with their marriages because they have so much more unmet expectations," Ho says.

In the face of social changes that have led to higher Chinese divorce rates - like more liberal values and women's financial independence - marriage researchers are suggesting that pre-marital and post-marital courses be institutionalized.

"Some people think sex is love, physical attraction is love, or money, a house and a car is love. Love has become commodified," says Chen Yiyun, a sociology professor at the Chinese Academy of Social Sciences, who studies Chinese marriage and family.

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"Nobody teaches you how to be a real husband or wife.

"If you can invest so many years of education for your career, why can't you do the same for a marriage you're supposed to have for 50, 60 years or more?" she says.

In the China of old, it was Confucian principles that taught men and women about family commitment and responsibilities. The elderly Zhang himself credits Confucianism for instilling in him the importance of harmony in his eight-decade marriage.

The challenge now is for young Chinese men and women to find their way back to the bedrock of a long, happy and healthy marriage. Otherwise, everlasting love will always remain just beyond their embrace.

Xu Lin contributed to this report.