Couples kiss during a kissing contest in Wuhan, Hubei province, November 23, 2014. Some 20 couples attended the contest and the winners have been awarded an iPhone 6, according to local media. (Photo by Reuters/Stringer)

Couples take part in a competition during a mass wedding of 64 doctoral student couples at Harbin Institute of Technology, a university in Harbin, Heilongjiang province, China, June 4, 2017. (Photo by Reuters/Stringer)

Photographer Ma Hongjie has spent 11 years documenting families in various parts of China for his upcoming book The Family Belongings of Chinese People. Here: a couple with their belongings and vegetables in Hebei Huailai county. (Photo by Ma Hongjie)

A couple kisses during a LGBT Pride parade in Oviedo, northern Spain, June 28, 2016. (Photo by Eloy Alonso/Reuters)

A couple embraces at the San Fermin festival in Pamplona, northern Spain, July 10, 2016. (Photo by Eloy Alonso/Reuters)

A couple joke as they walk on the beach on August 22, 2018 in Wonsan, North Korea. (Photo by Carl Court/Getty Images)

Close up of a couple, with the woman holding the man's knee, underneath a table. (Photo by Peter Dazeley/Getty Images)

A wedding couple poses for a photographer during a wedding photo shoot March 9, 2011 in Hanoi, Vietnam. Its is traditional for middle and upper class Vietnamese couples do a wedding fashion shoot posing for wedding portraits a few weeks before the wedding so that a wedding photo book is produced. (Photo by Paula Bronstein /Getty Images)