Jealous

The atmosphere is very depressing as Nie Fan and Kong Weijun wallow in their sadness, as well as helplessness due to them being unable to help with Su Yu's current condition. They feel at a loss, especially since even Li Ke who is more knowledgeable than them due to his current abilities also doesn't know how to solve (for good) Su Yu's current condition.

Li Ke looked at them and sighed. He could feel the two's sadness and frustration even if the two didn't speak or cry. Just by looking at the two's eyes which are filled with vicissitudes of life, he knows that Kong Weijun and Nie Fan deeply care for Su Yu.

Also, Li Ke has friends before, too, so he can understand how Nie Fan and Kong Weijun felt when a friend not only was injured but also is dying. No words are needed to be said to show sympathy.