He spends his nights sending "flares"—text messages he types but deletes, or calls that end in a hang-up after one ring. He’s looking for a sign that she’s feeling the same isolation. He thinks, "I'm lonely like a castaway," watching her life continue through the glowing porthole of a phone screen. She’s at parties; she’s smiling. She isn't stranded; she’s found a new continent.
The bridge of the song— "Heartbreak is a mess, a soul-searching quest" —kicks in as the walls of the apartment begin to feel like they’re closing in. The silence becomes deafening. He realizes that being a castaway isn't just about being alone; it's about the hope of being rescued. But the person he’s waiting for is the one who sank the ship. 5SOS - Castaway
The story ends with him standing on a busy street corner. He is still lonely, but he is no longer stranded. He’s walking among people again, a survivor of the wreck, finally ready to find his way home—even if "home" is no longer a person, but himself. He spends his nights sending "flares"—text messages he