So, why would a song dealing with a suicide sound rather upbeat? It’s not the first song on that general theme by this band; Cut Here is more what you’d expect, a reminder that you can miss the clues (if any) and then it’s too late, and the regret of that, which I’m sure a few of us have experienced by now. But The Reasons Why is far more edgy.
Somewhere, a while back, I read a moronic, very short review of 4:13 Dream, where the reviewer was assuming that the song was Robert Smith being some kind of gothic drama queen, and as per that stereotype, crooning about his own potential suicide. If you look up the lyrics on genius.com, it does have a note that this is about an actual suicide note sent to Robert Smith by someone he knew, way back in 1987.