It’s a lovely song. Here’s the lyrics. It could be recovery from an unrequited love, a love lost to breakup, or lost to death. It’s hard to say whether the word “death” is meant literally of figuratively. If I were the song writer, I would have deliberately written in the ambiguity I see there so that it could be meaningful to a wide audience, from those whose first teenage crush end up seeing their admiration blow up in their faces to jilted lovers just recovering from the shock of a love gone bad; and finally, to those who have lost to death someone who seemed to be vital to their every breath. I suspect the poet who crafted those lyrics meant them to cover all the above.