Ms. Hahn said, “Even a friend of mine confided to me that when he sees a Korean woman walking with a foreign man, he feels as if his own mother betrayed him.”

In South Korea, a country repeatedly invaded and subjugated by its bigger neighbors, people’s racial outlooks have been colored by “pure-blood” nationalism as well as traditional patriarchal mores, said Seol Dong-hoon, a sociologist at Chonbuk National University.

Centuries ago, when Korean women who had been taken to China as war prizes and forced into sexual slavery managed to return home, their communities ostracized them as tainted. In the last century, Korean “comfort women,” who worked as sex slaves for the Japanese Imperial Army, faced a similar stigma. Later, women who sold sex to American G.I.’s in the years following the 1950-53 Korean War were despised even more. Their children were shunned as “twigi,” a term once reserved for animal hybrids, said Bae Gee-cheol, 53, whose mother was expelled from her family after she gave birth to him following her rape by an American soldier.

Even today, the North Korean authorities often force abortion on women who return home pregnant after going to China to find food, according to defectors and human rights groups.

“When I travel with my husband, we avoid buses and subways,” said Jung Hye-sil, 42, who married a Pakistani man in 1994. “They glance at me as if I have done something incredible. There is a tendency here to control women and who they can date or marry, in the name of the nation.”

For many Koreans, the first encounter with non-Asians came during the Korean War, when American troops fought on the South Korean side. That experience has complicated South Koreans’ racial perceptions, Mr. Seol said. Today, the mix of envy and loathing of the West, especially of white Americans, is apparent in daily life.

The government and media obsess over each new report from the Organization for Economic Cooperation and Development, to see how the country ranks against other developed economies. A hugely popular television program is “Chit Chat of Beautiful Ladies” — a show where young, attractive, mostly Caucasian women who are fluent in Korean discuss South Korea. Yet, when South Koreans refer to Americans in private conversations, they nearly always attach the same suffix as when they talk about the Japanese and Chinese, their historical masters: “nom,” which means “bastards.” Tammy Chu, 34, a Korean-born film director who was adopted by Americans and grew up in New York State, said she had been “scolded and yelled at” in Seoul subways for speaking in English and thus “not being Korean enough.” Then, she said, her applications for a job as an English teacher were rejected on the grounds that she was “not white enough.”