I will answer you.

The darkness surrounding the ice pillar was still standing there when Bing Xian noticed that Shi Yue's body had stopped giving a life reaction.

'...'

Although she was a deathly cold woman from whom hardly ever a word of affection was heard or who was never seen with a trace of sadness on her countenance, this time was different.

To her, Shi Yue was like her closest sister. A woman she met thanks to Tang Yin back then, but who gradually became an important piece in her heart, like a younger sister.

They practiced, learned from Tang Yin, improved, and were often seen together.

When it was a critical moment for Tang Yin, a moment they never expected to see in their lives, they each made a decision to make a promise to an existence they did not know where they came from.

That promise separated them and prevented them from conversing for thousands of years.