Zhao Cang's lover didn't entirely rely on him, but her channels to connect with the lower realm were extremely limited.
The only thing she could offer was the secret to becoming a god that Zhao Cang held, and she had to prepare for all possibilities.
She sought him out because he had several fixed sects in the lower realm that supplied talent to their power.
She went to great lengths to arrange an old servant for Zhao Cang, which had cost her a fortune.