Singer asks his beloved to marry him. She refuses; she loves him, but is pledged to another. Ch.: "I cannot be your sweeheart, I cannot stay by your side, Another is patiently waiting, waiting to call me his bride, My heart it is almost broken,,,,"
Singer courts his beloved, asks her to marry him. She refuses, saying that though she loves him, she's promised to another. They part; he pines. Chorus: "I cannot be your sweeheart, I cannot stay by your side / Another is patiently waiting, waiting to call me his bride / My heart it is almost broken, your vows only add to my pain / I love you, sweetheart, I love you / Though we never meet again"
A classic plot, but apparently not a member of another song family. Nor could I find it in sheet music; possibly Howard or Peak wrote it. - PJS