not have the heart to do

not have the heart

To not have the emotional resolve (to do something); to be unable to do something, especially that which is or seems callous or unsympathetic. I didn't have the heart to tell her that I didn't love her anymore. How could you fire someone the day after their father died? I wouldn't have the heart.
See also: have, heart, not
Farlex Dictionary of Idioms.

not have the heart to do something

Fig. to be too compassionate to do something. I just don't have the heart to tell him the bad news.
See also: have, heart, not
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.
See also:
  • not have the heart
  • not have the heart to
  • have no heart for
  • have no heart for (something)
  • have the heart
  • have the heart (to do something)
  • play the heavy
  • play the heavy, to
  • poor little rich girl
  • poor little rich girl/boy/kid