This is the 4954th most frequent Korean word.
그러던
"그러던" means "was doing so" or "was in such a state."
In this sentence, '그러던' refers to a state of things as they were ('that way') before describing a subsequent event.
그러던 시간이 점점 흘러가면서 우리는 친해졌어요.
Time passed like that, and we became closer.
Here, '그러던' sets the background state ('things being like that') before introducing a significant change or event.
그러던 어느 날, 나는 그를 우연히 다시 만났어요.
One day like that, I happened to meet him again by chance.
'그러던' is used to illustrate an ongoing state or situation prior to discussing a sudden development.