Young couple in BDSM action on the leather sofa. (Photo by Alamy Stock Photo)

Couple getting intimate on couch. (Photo by Vincent Besnault/Getty Images)

A girl walks along former railway tracks in the so- called “Tunnel of Love”, surrounded by arches of intertwined trees, near the Ukrainian village of Klevan, Rivno region, on August 6, 2018. The tunnel of about five kilometres in length is a botanical phenomenon, which became a cult place for tourists and couples in love. The tourist legend says that wishes of couples in love will come true, if the couple passes through the tunnel. (Photo by Sergei Supinsky/AFP Photo)

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)

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 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)