An adverb before 떠나다, to leave or depart. Most of these lines just point back at how it happened with like that, but the vivid ones are emotional: a taxi that pulls away cruelly before he can hail it, someone leaving awkwardly, a co-star leaving coldly the moment the take ends. 떠나다 is departing from a place or a person, and it is also the verb for setting off on a trip, which is one of these lines.