Lan Wangji considers Luo Binghe a threat to nearly everyone, but it is a pertinent question, regardless. If there is something about him specifically that threatened Aornis, it is worth knowing. He asks it.

"Luo Binghe would visit her dreams, and they would fight. She would take the memory, but he returned again and again. Shen Yuan and Luo Binghe were suspicious of her. The entire mansion was suspicious. There were clues, but no proof. They were investigating."