"A torch song is a sentimental love song, typically one in which the singer laments an unrequited or lost love, where one party is either oblivious to the existence of the other, or where one party has moved on." (Wikipedia) Sarah Vaughn, Broken Hearted Melody.  Timi Yuro, Hurt.  Billie Holliday, The Very Thought of You.  Roy Orbison, In Dreams.  Peggy Lee, Oh You Crazy Moon.  Ketty Lester, Love Letters.  Etta James, At Last.  Lenny Welch, Since I Fell For You.