Before leaving, Su Yuan informed Xu Anyan about his plan to go to the Abyss with Shangguan Meng to hunt down the Blood Apostle.
Xu Anyan was already used to his occasional trips to the Abyss. She didn't think much of it, as with Su Yuan's current strength, clearing that Abyssal Nest was no problem.
As for going with Shangguan Meng, whatever meaning or symbolism that might have... she wasn't interested.
They went, and that was that.