The fact you remember the exact chapterIm pretty sure that he has already seen her face when she kissed him around chapter 150. One of the first arcs.
It's much earlier than than... chapter 75 of the manhua she takes off her veil to kiss him and extract the profound yin whatever from him to reach the true element stage. She completely took it off and revealed her face. It also wasn't the first time she'd taken off the veil. She did so when the high heaven sect master approached during YK's Promotion to the initial element realm, just to introduce herself.The fact you remember the exact chapter