Three things led to multiple departures from one of South Korea's top pop groups, says one expert.

At the 2015 World Knowledge Forum held in Chengdu, China, on May 20, an industry insider known as President Wang discussed several issues with the Korean entertainment industry that could have led to several Chinese K-pop stars leaving their idol groups and heading to China.

The lack of importance placed on the film industry, the smaller income of celebrities in Korea versus China, and the entertainment agency system were all problems that make it difficult for Chinese entertainers in Korea, claimed Wang. 

The topic remains a highly controversial one in South Korea, where fans of SM Entertainment's popular idol group EXO have struggled with the departures of EXO's former members Kris and Luhan in 2014, followed by the two entering the Chinese film industry.

Wang highlighted the differences between the Korean and Chinese entertainment industries as some of the issues. He pointed out that the most important aspect of the Korean entertainment industry is the music industry, while China focuses more on film.

"When Chinese celebrities complete their training in Korea, they attempt to move into the film industry," said Wang. "However, if the Korean entertainment agencies fail to provide this career path to their artists, it is likely that they [the Chinese celebrities trained in Korea] become worried for their future."

The discrepancy in the size of income that celebrities make in each market is also a possible factor.

"At least 20-30 Chinese celebrities make around 100 million yuan (an estimated $17.5 million) a year," Wang revealed. "However, Korean celebrities make far less. So if an artist has to pick one market to work in, the answer is clear."

Further highlighting the differences, Wang explained that in China the modern system makes the artists stronger in comparison to their representative agencies while the entertainment agencies hold greater power in South Korea. He further suggested that Korean entertainment companies could keep Chinese members from leaving by working in greater cooperation with the Chinese entertainment industry.

Wang also suggested that Korea take steps to avoid further Chinese national K-pop idols leave the Korean entertainment industry.

The forum comes at a time when it is unconfirmed whether a third Chinese member, Tao, also left EXO.  A member of another SM Entertainment act, Super Junior's former member Han Geng, left Korea in 2009 to return to China to pursue a career.