I saw this youtube video and what was in it shocked me
So in lovesick girls jennie, lisa and rosé commit suicide cuz they were lovesick ever since they boyfriend ditched them or smth. jennie died from a car accident, lisa jumped off a building and rosé drowned herself in black ink. jisoo tried to save them but she was too late but she kept their souls in the hourglass. two years later, she learned black magic and revived them in similar ways they died. jennie came back from another vehicle, lisa was in the basement of the building she jumped off and rosé was on top the the ink she drowned in.
But i have something to add. in playing with fire, the first line literally translates to 'mom told me to watch out for boys' which of course they never listened to and ended up dying. and in kill this love, we see rosé driving and running away and i think that from a year ago (timeline wise) she was already in a bad relationship. after a year, she and the other two girls can't stand it anymore...
Of course this was probably was only meant for visuals and effect but this still may be a possibility.