Aharon is related to the crown in other ways as well. Sometimes you learn about the source of a soul from its flaws. Something that for a certain soul is a blemish or a flaw is a pointer for the Arizal to indicate where that soul came from, because the individual who has that soul must rectify its source. As great as Aharon was, and as much as he was the epitome of love, something went wrong with him: He by mistake caused the Jewish people to create the Golden Calf. He allowed the people to sin, which is why the Torah says the Golden Calf was made by Aharon.
Some of the events of that tragic event are not completely explicit in the Torah (but the Torah hints to them). Aharon had a nephew whose name was Hur, the son of his sister Miriam. We first meet Hur when Moses sends Joshua to fight Amalek. Moses goes up the mountain and lifts his arms with Aharon and Hur supporting them, so that Joshua could vanquish Amalek. Later, Moses leaves Aharon together with Hur in charge before he ascends Mt. Sinai to receive the Torah. But later, Hur is nowhere to be found.
What happened to Hur? The sages say that Hur tried to act responsibly and rebuke the people for wanting the Golden Calf. As a result, they murdered him. Aharon saw this and realized that his fate would be the same if he tried to stop the people from pursuing this idolatry. All this is described in the Talmud.
