What had happened when Laurana met Kitiara up on the walls of the High Clerists' Tower?

When Laurana met Kitiara on the walls of the High Clerists Tower, something had gone out of her. Flint speculated that it was something that Kitiara had either done or said, and due to the fact that it seemed to snuff all the light out in Laurana, he speculated that it was something to do with Tanis, Laurana's first and only love.