Kim Jong-un's wife, Ri Sol-ju's frequent appearance reflects Kim Jong-un's young age complex. It's only been 2 to 3 years Kim Jong-un appeared in the official public. So, his young age, in his mid to late 20s, and incompetence as a leader of nation would not be desirable for the North Korean people.
By bringing in Ri Sol-ju into the public scenery, Kim Jong-un is emphasizing that he is a perfectly capable adult who has a wife. In addition, he is using Ri Sol-ju's unprecedented actions to emphasize Kim Jong-un's an open minded leadership.
However, this phenomena is an action that was extensively calculated, so you should not be fooled by the appearances. Kim Jong-un visited military troops to stimulate his soldiers for the preparation of war. Just like his predecessors, he is a dictator uninterested in stabilizing the livelihoods of the public, but only interested in unification under communism.