After the Wayland affair, Mara feels slightly optimistic about their...whatever it is. Luke gives her that lightsaber, she splits her time between Karrde's organization and the Smugglers' Alliance, and they always stop to chat whenever she's on Coruscant for business.
But things change. He finds other Force-sensitives, and stops pestering her to train with him. Back during the Thrawn crisis, she was special: the only one (besides his sister) with the same gifts and potential. Not anymore. Luke doesn't lose interest so much as find new ones that slowly edge her out.
She holds strong to her sense of superiority-after all, she was the Emperor's Hand-until even that is stripped from her. She goes from believing herself the only Hand to realizing that she was merely one of many, an insignificant pawn like the rest.
Sometimes, he remembers her. She thinks it'd better if he just forgot her entirely.