Talk:心做し (Kokoronashi)/@comment-2600:387:3:801:0:0:0:84-20190215161806

My theory for translation note 2 -- 心臓 has a more anatomical meaning (used in medical conditions and such) wheras 心 is more of the "feeling/emotional" heart. So they're saying they just have the heart organ without a capacity to love the human back. See also at the end where they use 心 to ask where they would look for their (emotional) heart.