Hong Kong (CNN) Helen Zhang, 37, a former Beijing resident, moved to Hong Kong two years ago with her husband and, for the most part, loves it.

"The polite and orderly people make me believe this is what a civil society is supposed to be like," Zhang tells CNN.

A self-described foodie, she also loves the diverse cuisines on offer in the city. But says she doesn't care much for the stifling summer humidity.

Zhang is among a growing number of mainland Chinese calling Hong Kong home -- despite tensions between the city and China.

Last year, more than 37,000 mainland Chinese were granted permission to live and work in Hong Kong, up from 22,077 in 2010, according to Hong Kong's Immigration Department.

On top of that, another 40,496 got one-way permits in 2014, allowing them to settle in the city.

They come for different reasons -- to study, to reunite with family, to further their career, or to find a better quality of life.

But they don't always receive a warm welcome from Hong Kongers and there are some signs that the city's shine, at least for young and upwardly mobile Chinese, has dulled.

Friction

The influx of Chinese -- known locally as mainlanders -- since the former British colony returned to China in 1997, combined with frustration over political reform, has generated resentment among some Hong Kongers, particularly in the past three years.

Hong Kong, ruled under the principle of "One country, two systems," is officially part of China, but is allowed rights and freedoms unseen in other Chinese cities as a Special Administrative Region (SAR).

But Beijing has so far refused to grant a key privilege: Free and open elections for their own leader.

Frustrated Hong Kongers have tried everything to demand greater voting rights, from hunger strikes to massive street occupations, with no luck.

Chinese tourists are surrounded by protesters at New Town Plaza, a shopping mall in Shatin, Hong Kong during a rally against parallel-goods trading on February 15, 2015.

Day to day, much of the vitriol is aimed at traders and tourists -- the day trippers who flock to the city with wheelie suitcases and stock up on tax-free products -- but even long-term residents say they sometimes feel like outsiders.

Zhang says she's rarely felt she's been treated differently, although cultural differences and the language barrier -- most Hong Kongers speak Cantonese rather than her native Mandarin -- has made it hard for her to make local friends. However, she says this doesn't bother her.

"Really good friends need to share many common interests and values," she says. "With some people you can have meals together once in a while but you just can't be friends."

It's an experience shared by Yang Lulu and Bill Hong. The couple moved to Hong Kong from the Chinese mainland to pursue master's degrees.

They both landed jobs in the city after graduation and stayed for more than two years.

"There are more similarities between the two cultures than differences," says Yang.

Still, Yang says that sometimes they felt lonely and, while they enjoyed professional relationships with colleagues, they rarely hung out after work.

"They are more individualistic, and tend to draw a clear line between private life and work life," Hong says.

Yang Lulu and Bill Hong in their Hong Kong apartment.

Their biggest complaint, however, was the high cost of housing. They say half their monthly income goes into renting a place "only a bit bigger than a closet."

Identity

It wasn't until the Occupy Central protests that erupted in the city last September, that Yang realized that her colleagues differentiated between Hong Kongers and Chinese to such an extent.

"They used phrases like, 'we Hong Kongers,' 'those Chinese.'"

She felt offended at first but later realized that her colleagues didn't see her as a mainlander.

"They think I'm a Hong Konger because I studied here and now work here," she says. "But if you are just a tourist, you are Chinese."

Zhang says she followed the protests "voraciously" and her Cantonese got a boost as a result. But later, she grew irritated as the protesters blocked traffic on some of the city's main thoroughfares for weeks.

She also plans to steer clear of the protest march scheduled for Wednesday, July 1, the 18th anniversary of Hong Kong's return to China.

Fading allure

But with signs the rift between the city and mainland China is widening, Hong Kong's allure to young and upwardly mobile Chinese could be fading.

This weekend, police arrested five people and used pepper spray to disperse a crowd protesting against a group singing in Mandarin in the district of Mong Kok, according to the South China Morning Post.

Protesters march to a shopping mall in Shatin, Hong Kong February 15, 2015. One protester holds a placard with a picutre of a locust.

It was the latest incident in a growing localist movement -- a broad term for hardline groups resisting Chinese influence over the city.

In recent months, protesters waving placards describing mainland shoppers as "locusts" have hurled abuse at Chinese tourists and scuffled with police.

Fear of being on the receiving end of such hostility is deterring Chinese students from applying to undergraduate courses at Hong Kong's universities, according to a report last week from the state-run Xinhua news agency.

Applications to Hong Kong Polytechnic University, Lingnan University and Hong Kong Baptist University for the upcoming academic year have fallen between 34% and 40%, the report said.

And the specter of what some believe is an ethnic conflict is prompting some long-term Chinese residents to turn their back on the city.

In an anonymous farewell letter that went viral on Chinese social media earlier in June, a mainland resident wrote that in the seven years he lived in the city he was "used as a punching bag for mainland-Hong Kong frictions."

According to a translation published online by Foreign Policy, the author planned to move across the border to the southern Chinese city of Shenzhen, spurning the opportunity to become a Hong Kong permanent resident.

Yang has just moved back to the mainland too. Her boyfriend was offered a job opportunity at an international bank in his hometown of Xiamen.

She wasn't looking to leave but has no regrets.

"Now that I'm back, I don't think I'll miss Hong Kong -- the quality of life is so much better here, at least we live in a place much bigger than a closet."