I remember hearing this song with my older brother the year our older sister went away to college. I missed her terribly, and my brother asked me if this song made me think of how I felt with her gone, and it did. Looking at the lyrics it could be a breakup, but it's clearly a separation and the emotion is so strong that you can't sleep. It's written generally enough it could be about any of those situations.
I remember hearing this song with my older brother the year our older sister went away to college. I missed her terribly, and my brother asked me if this song made me think of how I felt with her gone, and it did. Looking at the lyrics it could be a breakup, but it's clearly a separation and the emotion is so strong that you can't sleep. It's written generally enough it could be about any of those situations.
It is a great pop song.