I think the line 'Why I was the one worth leaving' means he's seeing why he was the one people always left behind and now in the line 'And I am finally seeing why I was the one worth leaving' He realizes why people always left him for someone else. I think a big theme in this song is loneliness, as this line is repeated and the title The district sleeps alone tonight also has direct references to loneliness. The 'Into the loneliest evening' also references loneliness.
I think the line 'Why I was the one worth leaving' means he's seeing why he was the one people always left behind and now in the line 'And I am finally seeing why I was the one worth leaving' He realizes why people always left him for someone else. I think a big theme in this song is loneliness, as this line is repeated and the title The district sleeps alone tonight also has direct references to loneliness. The 'Into the loneliest evening' also references loneliness.