How is she at fault when there’s no way she would know Ao Zhen’s habits? If he wanted his door locked, he should have locked it himself or told her.
Actually Li Shi Ying was also at fault here since she didn't lock the door when Long Ao Zhen always make sure to lock the door because he knew that stalker Han Aoman would always find opportunity to barge to his room.
This is a story worthy of a re-read. Great plot, dynami characters, and interesting developments that perfectly explain how the FMC ended up the way she did.