Pakistani people buy flowers on Valentine's Day in Islamabad, capital of Pakistan on Feb. 14, 2015. (Xinhua/Saadia Seher)

A Pakistani couple carrying balloons walk along a road on Valentine's Day in Islamabad, capital of Pakistan on Feb. 14, 2015. (Xinhua/Saadia Seher)

A couple make a heart-shaped gesture under the cherry trees near Riyue Tan, or the Sun Moon Lake, in Nantou County, southeast China's Taiwan, Feb. 13, 2015. (Xinhua/Jin Liwang)

Pakistani girls look at decorations on Valentine's Day, in Karachi, Pakistan, Feb. 14, 2015. (Xinhua/Masroor)

A couple poses during a collective wedding in Zocalo Square in Mexico City, capital of Mexico, on Feb. 14, 2015, the Valentine's Day. (Xinhua/Alejandro Ayala)

A person buys flowers in the city of Tegucigalpa, Honduras, on Feb. 14, 2015, the Valentine's Day. (Xinhua/Rafael Ochoa)

Couples kiss during a collective wedding in Zocalo Square in Mexico City, capital of Mexico, on Feb. 14, 2015, the Valentine's Day. (Xinhua/Alejandro Ayala)

A couple kisses during a collective wedding in Zocalo Square in Mexico City, capital of Mexico, on Feb. 14, 2015, the Valentine's Day. (Xinhua/Alejandro Ayala)

A Yemeni man prepares flowers for customers on the Valentine's Day in Sanaa, Yemen, Feb. 14, 2015, amid the political and economical unrest the country has witnessed. (Xinhua/Hani Ali)

A Yemeni man prepares flowers for customers on the Valentine's Day in Sanaa, Yemen, Feb. 14, 2015, amid the political and economical unrest the country has witnessed. (Xinhua/Hani Ali)

A Yemeni man waits to buy flowers for the Valentine's Day in Sanaa, Yemen, Feb. 14, 2015, amid the political and economical unrest the country has witnessed. (Xinhua/Hani Ali)

An Egyptian vendor displays gifts in front of a shop decorated for Valentine's Day in Cairo, Egypt, Feb. 14, 2015. (Xinhua/Ahmad Gomaa)

An Egyptian vendor displays gifts in front of a shop decorated for Valentine's Day in Cairo, Egypt, Feb. 14, 2015. (Xinhua/Ahmad Gomaa)

Two Egyptians hold a heart-shaped gift and flowers at a shop decorated for Valentine's Day in Cairo, Egypt, Feb. 14, 2015. (Xinhua/Ahmad Gomaa)

Girls with red roses are seen on the street on the Valentine's Day in downtown Zagreb, capital of Croatia, Feb. 14, 2015. (Xinhua/Miso Lisanin)

A man with a red rose is seen at a flower market on the Valentine's Day in downtown Zagreb, capital of Croatia, Feb. 14, 2015. (Xinhua/Miso Lisanin)

A bunch of red roses is seen at a flower market on the Valentine's Day in downtown Zagreb, capital of Croatia, Feb. 14, 2015. (Xinhua/Miso Lisanin)

 People sell heart-shaped balloons on the Valentine's Day in Quito, capital of Ecuador, on Feb. 14, 2015. (Xinhua/Str) 

A man sells heart-shaped balloons on the Valentine's Day in Quito, capital of Ecuador, on Feb. 14, 2015. (Xinhua/Str)

A woman sells heart-shaped balloons on the Valentine's Day in Quito, capital of Ecuador, on Feb. 14, 2015. (Xinhua/Str)