Judging by the personality Avera had shown, Fang Zhen thought otherwise.
He deduced that Avera had intended to take the Path of the Dead from the very beginning. She must have had a way to deal with the specters and wasn't as helpless as she claimed.
That was all just an excuse, a performance.
If things had gone south, Avera surely had a way to save her own skin or escape.
She likely dragged Fang Zhen along because she wasn't confident she could defeat the Forbidden Realm Gatekeeper on her own and needed him for grunt work.
Of course, while Avera was using Fang Zhen, he was also using her.
They were simply using each other to get what they wanted.
