The Story Of The Song: The song tells the story of two lovers who have said goodbye to each other and the narrator explaining that he/she “can’t live if living is without you.”
The Story Behind the Song: The song was written by a band called Badfinger, which was supposed to be the heir apparent to the Beatles. Paul McCartney even produced some of their music. The verses were written by Pete Ham (and were inspired by his girlfriend at the time, Beverly Tucker) and the chorus by Tom Evans (about his future wife, Marianne). After that, things went kind of south for Badfinger. Pete Ham committed suicide in 1975 by hanging himself and Evans followed suit in 1983 after the band was cheated out of royalties. So, in a way, it’s a much sadder song than you think.
As for the famous covers…
Nilsson covered the song after hearing it at a party–where he mistook it for a Beatles song–and Mariah Carey recorded it after hearing Nilsson’s version play in a restaurant because she figured it was a universal and eternal hit.