Hakoda and Ursa have never been seen interacting in the canon universe. They were on opposite sides of the war until it ended.
Hakursa is a very popular "crack ship" in the Avatar fandom. When it was revealed that Ursa was possibly still alive, many fans began to ship her with Hakoda as it was likely that she and Ozai were divorced, especially when the latter was incarcerated at the end of the war. Hakoda had been widowed since several years before the series started. A lot of fans also liked the fact that they were from nations of the opposite elements and some liked the idea of Zuko and Katara's families being brought together. Many fans were upset when they saw that Ursa got remarried to her childhood love Ikem as it proved this pairing to be impossible.