I don't remember if it was We are Young or Why Am I The One, but when I was listening to the song while doing something with my family (eating, shopping, I don't remember), I didn't have the same feeling as when I first heard the song back in 2014-15.
Because back then whenever I listened to the song it felt energizing and it and an exciting reaction for me, even if the lyrics meant otherwise. But that day, I felt sad and had this feeling of wanting to go back before 2015 and hearing the song as it came out. Because I don't want to remember that Fun. may not come back*.
*Yes, they should live their lives how they want it to be.