The So Sick singer sat down to write the words and melody to the song that would become Irreplaceable and recalled his relative ending her romance with an unfaithful boyfriend by placing his belongings in a box on the left of her closet.
The lyric Beyonce went on to sing became an instant classic as she urged her fictitious man to pick up his stuff in the box on the left.
In a new Vh1 Behind The Music TV special, which will air in America on Sunday (23Sep12), Ne-Yo recalls coming up with the idea for the song: "I remember this story of an aunt of mine who was dating this guy who was cheating on her... She had a really good job at the time and she bought him all of this stuff.
"I remember him coming to the house and him looking in the closet and going, 'Where's my this, where's my that?' and she said, 'Oh, in the box to the left of the closet. Everything you own is in that box and everything I bought is over here.'"
The song came together very quickly and Ne-Yo initially planned to record it himself, but a chat with record boss L.A. Reid made him realise it was a better fit for someone like Beyonce.
Reid recalls, "We both kind of agreed that this isn't something that a guy should be saying to a girl and the next time I heard it it was Beyonce.
"I don't think that Ne-Yo regretted not recording Irreplaceable. When the mailman knocked on the door and said, 'Sir, here's your cheque,' I think he was a really happy man that day."