A young couple with matching expressions stare nervously into the camera with deep brown eyes. He, a Vietnamese student, has just met the love of his life. She, a North Korean, is forbidden to love him back.

It was 31 years after Pham Ngoc Canh, 69, took that first photo of Ri Yong Hui, before the two were finally allowed to get married in 2002 when North Korea took the rare step of allowing one of its citizens to marry a foreigner.

“From the moment I saw him, I was so sad because I felt it would be a love that could never be realised,” said Ri, 70, speaking from the small Soviet-era apartment she and Canh share in the Vietnamese capital, Hanoi.

Now enjoying freedoms in Vietnam that would be impossible in North Korea, Canh and Ri are hoping the upcoming summit between US President Donald Trump and North Korean leader Kim Jong Un in Hanoi will help end hostilities with Pyongyang.

Back in 1967, as Vietnam and the United States were locked in war, Canh was one of 200 Vietnamese students sent to North Korea to gain the skills the state needed to rebuild itself once the war was over.

Several years later, during a chemical engineering apprenticeship at a fertiliser factory on North Korea’s east coast, Canh spotted Ri working in a laboratory.“As soon as I saw him, I knew it was him,” said Ri. “He looked so gorgeous”.

“Until then, when I had seen so-called handsome guys I hadn’t felt anything, but when he opened the door, my heart just melted”.But there were challenges. Until this day in North Korea, and in Vietnam at the time, relationships with foreigners are strictly forbidden.