If u look into the bomb chapter again, we have a few scene from the past and I believe he die while try to save Taeyi from the bomb, that why she felt guilty. And if I remember correctly, when Taeyi try to jump out the window with the bomb, she say she felt bad for doing the same thing as Ming dude (still don’t know his name) and it will make the ML felt guilty like her.
That how I view it as so maybe I could be wrong though ╮( ̄▽ ̄)╭

wait can someone tell me how mhyungho (srry can’t spell it right) died again? i can’t remember or did they tell us?