Dubbed as "Song-Song couple," both have huge followings across Asia and elsewhere. They married in October 2017 after falling in love while co-starring in the mega-hit TV drama, "Descendants of the Sun." They are one of the highest-profile star couples in South Korea's entertainment world.

A law firm representing Song Joong-ki confirmed that he was taking legal steps to divorce actress Song Hye-kyo.

The 33-year-old actor offered an apology to his fans because he had to deliver "not good news," according to the Seoul-based Lee & Ko law firm.

Song Joong-ki said he won't disclose details about why he and 37-year-old Song Hye-kyo want to end their marriage. He said both want to end their divorce proceedings smoothly rather than blame each other.

Song Hye-kyo's management agency, the United Artists Agency, said "a personality difference" is the reason for the divorce.

"Song Hye-kyo is taking steps for divorce after cautious considerations with her husband," the company said, according to Yonhap news agency. "The reason is a personality difference, and the two sides inevitably made this decision, unable to overcome their differences."

The names of the couple were the most searched words on main portal sites in South Korea and China for much of Thursday. Many fans issued messages on online sites expressing their sadness over the divorce.