Two years ago, Lin Tianfu exhibited Love of Half a Century at the Pingyao International Photography Festival. His black-and-white images depicted 200 elderly couples from all but one of China's 56 ethnic groups, along with a summary of their love stories.

Zhang Mucheng and Xu Dongying live in the Shanghai home. Huang Xiudi, their daughter-in-law, helps take care of them. [Photo by Gao Erqiang/China Daily]

The photographer from Taiwan undertook the massive project in 1997, saying it was something "fragile modern marriages can use for reference".

After 14 years of criss-crossing China in search of ordinary couples who have been married at least 50 years, what insights has he gained from these enduring unions?

"Couples should empathize with each other, think more about their partner's welfare and not be too materialistic or self-centered," says Lin, his words echoing Zhang Mucheng's own attitude toward marriage.

The subjects that left the deepest impression on him, Lin says, are a couple from Yunnan province's Naxi ethnic group. During the "cultural revolution", the husband was charged for being a counter-revolutionary and imprisoned for a year.

On top of being a mother, his wife took on the role of family breadwinner while encouraging him to stay hopeful. After his release, she continued to support the family financially since he was too sick to work.

He later founded an herbal clinic that now serves both Chinese and foreigners.