if you read the comments below, the illustration was not done well according to the novel. here is grayson's pov https://novelingua.com/desire-me-if-you-can-chapter-035/
He left because he thought that no one would stay in that building that will fall abt moment, so Dane will also come out.
aaahhh.. the novel explains his way of thinking significantly better than the manhwa. in the manhwa it seemed like he gave up because he couldn‘t be bothered with, while the novel shows he left because he was aware of his limited knowledge. got it.. thank you for looking up the chapter!
and it was mainly because he can see how dangerous it was. the building collapsed after he went out. dane left him and he cannot follow and he doesn't want to risk his life too
I can‘t believe he just left dane in there. I‘m genuinely speechless