I think the tone is that of disillusionment, disenchantment too.When two people have to separate, for one reason or other there is suffering and dissapointment.The feeling is universal and that is the tone the author conveys through his poem.It is the distance between a woman he once loved and himself he is grieving about.
I can confirm this is the correct answer as I have individually tested most of the questions for Bryon, Shelley, and Keats test and it showed up as correct.
