Taylor penned this track when she was sitting on her tour bus after a show thinking about a relationship that ended several months previously. She explained to Billboard magazine: "The feeling wasn't sadness and anger or those things anymore. It was wistful loss. And so I just got my guitar and I hit on the fact that I was thinking in terms of rhyming; I rhymed magic with tragic, changed a few things and ended it with what a sad beautiful tragic love affair. I wanted to tell the story in terms of a cloudy recollection of what went wrong. It's kind of the murky gray, looking back on something you can't change or get back."
Red covers the whole rainbow of emotions and this song lies at one certain spectrum of color. "I'm 22," Swift told Billboard magazine. "I'm all over the place, so my record is all over the place. Part of this record is acknowledging all these emotions are very loud and very different from one another. At one end of the spectrum you have 'Sad Beautiful Tragic,' which is a breakup song in the form of a funeral march, and you also have 'Never Ever Getting Back Together Again', which is a breakup song in the form of a parade." Taylor has a really amazing talent when iit comes with words and it never fails to amaze people all over the world. She really takes it to a new level with this one.
Although her collaborations on this album Red are big hits, it is this one--one she wrote on her own--that really sets everything in motion. She has never done a song like this before but she did it so well. This song sounds very mature and restrained. The vocals are perfectly controlled and there is only minimum accompaniment. Its mood is irresistibly sad and lovely at the same time.
This is about how two people are in love, but cannot be together because everything is against them- distance, timing, break down, fighting, silence (as the bridge says).
This can also talk about long distance relationships who never worked out and the imagery from this song is so strong that it feels like it was taken from a movie scene where a young girl sends off her lover (maybe an army or navy) to a train ride.
In the end, she is not mad at what happened, but she thinks it is a beautiful tragic love affair.
The song speaks for itself, not exactly rocket science. Love is sad, beautiful and tragic.