But according to Thae Yong Ho, the senior North Korean diplomat who fled Pyongyang's embassy in London, Ri Sol Ju's status as a "commoner" in North Korea's classification system means she is not quite in a position to hold influence over Kim's important decisions, South Korean news network MBN reported Tuesday.
Kim Yo Jong, the North Korean leader's younger sister, is more powerful than Ri, and directs all major public events, according to the report.
The younger Kim can often be seen on North Korean television, including the Seventh Party Congress, darting from one place to another as she accompanies her brother in state ceremonies.
But Kim Yo Jong does not preside over the idolization of the Kim family because she does not have the "intellectual fitness" to conduct such affairs, Thae said.
She is not as powerful as her older brother, but in her presence even senior officials stand to show respect, the former North Korean diplomat added.
Ri, by contrast, is a "commoner" who cannot criticize her husband. Thae also said it wasn't clear whether the North Korean first lady "has captured Kim's heart."
Thae, who has been busy with press conferences and interviews in December, has been supplying South Korean reporters with new revelations about the North Korean regime.
Thae said this week that he hopes to return to Pyongyang once unification of the two Koreas is achieved. Thae also said his dream is to build a highway that will link Seoul to the Chinese border city of Dandong, according to South Korean news network Channel A.
The number of North Koreans who defected to the South increased in 2016.
According to Seoul's unification ministry, 1,414 refugees sought asylum in the South last year.
The total number of defectors now stands at 30,208, South Korean newspaper Donga Ilbo reported.