When Britain voted to leave the EU, my husband - who is a UK citizen - was upset. Among the many things that worried him were fears that his island country's economy would decline, it would become a lot less cosmopolitan and tolerant, and he would lose the convenience of traveling to EU countries without applying for a visa. "In the future when we go to Spain for a vacation, I have to apply for a Schengen like you do," he lamented.

My Chinese passport gives me little advantage when it comes to traveling. I have to make visa applications for just about every country I want to visit, whether they are in the EU or somewhere else. But I am upset by the UK's exit too. Besides worrying about its impact on the world economy and being sympathetic to my poor husband who felt ashamed of his compatriots, Brexit put a big dent in my ideal for a world in which people from different cultures can live together boundlessly and harmoniously.

It turns out that the dissolving of national boundaries, even in a small part of the world, couldn't hold for long. The removal of border restrictions not only benefits travelers looking for short-term excitement but also migrants looking for long-term life changes.

The foreign-born population of the UK reached 8.3 million in 2014, more than double the 1993 figure, and those living in the country who were born in other EU countries reached 3 million in 2015. The locals panicked. Brexit indicates that the giant melting pot has boiled over.

I am not so naïve as to believe that people from different backgrounds can live together without conflict - there will always be tension, as in any big family. As the Disney blockbuster Zootopia accurately depicts, such a world is a place where prey and predator live together.

Through the film's rabbit character, Judy, a prey-turned-hero police officer, the movie offered a practical solution to multiculturalism.

"Real life is messy," says Judy. "We all have limitations. We all make mistakes. Which means - hey, glass half full! - we all have a lot in common. And the more we try to understand one another, the more exceptional each of us will be. But we have to try."

But that is a movie. In real life, where people are not wolves and sheep, the line between prey and predators can be blurred and confusing.

To immigrants who live in the UK, the locals may see those who are hostile to them as predators. But in the eyes of Brexit supporters, the Poles and Romanians who work in stores and on construction sites are the predators, stealing locals' jobs and driving down wages.

In the multiracial US, many minorities think they are prey. In the past, Native Americans lost their land. Nowadays, black people may be turned down for mortgage applications just because their names hint at their race. Asian professionals face glass ceilings when climbing the leadership ladder in corporations. All minorities feel forced to follow the social protocols set by those in control of the establishment, which largely means white people.

But in the eyes of some whites, the predators might be the black people who, they fear, are prone to street violence. With the help of Donald Trump's ugly rhetoric, some may see Mexicans as rapists (despite statistics), and all Muslims as potential terrorists.

The confusion is made worse by examples of countries where, on the surface, there appears to be a rosy multicultural picture.

When my husband and I were in Singapore recently, I was impressed by the vibrant local businesses served by people from different racial backgrounds and the relatively smooth relationships between them. I exclaimed that Singapore is a better model for a melting pot than New York.

I felt comfortable in the city-state, because I thought I didn't have to change myself to fit into the mainstream culture. Asian culture, particularly Chinese culture, is the mainstream there. And Westerners, a small minority, don't have to try too hard to assimilate either. Western culture is generally respected, and they can just live as they like. This sounds like a dreamland, where everyone is happy.

But even in this paradise, foreign workers suffer from abuse by their employers.

Some incidents involve domestic workers, such as maids, while others involve construction workers. The victims are mainly from places like the Philippines, Indonesia and Bangladesh.

It must be said, though, that the government works very hard to keep harmonious relations between the three main resident populations, people of Chinese, Indian and Malay origins.

While Chinese make up more than 74 percent of Singapore's population, and are generally doing very well, there are also opportunities for many others.

In Singapore, I just hope that I am neither predator nor prey.

The author is a New York-based journalist. rong_xiaoqing@hotmail.com