Heize's song "Sad Ending" (어쩌면 우리) tells the story of a relationship that has ended badly. The lyrics describe how the couple's story has ended like a bad habit, and how they wonder if this is really what their relationship was meant to be. They realize that they didn't know each other as well as they thought they did, and that they were never able to comfort each other properly. The chorus repeats the line "neowaui modeun iyagi" (all of our stories) to emphasize the idea that their relationship was made up of many different moments and experiences. The song also features a rap verse by george, in which he expresses regret for not leaving the relationship sooner and for acting foolishly. Overall, "Sad Ending" conveys a sense of disappointment and acceptance, as the couple come to terms with the fact that their love has not been enough to sustain their relationship.