Of killing the thing you love

OLIVIA

Even what it please my lord, that shall become him.

DUKE ORSINO

Why should I not, had I the heart to do it, Like to the Egyptian thief at point of death, Kill what I love?--a savage jealousy That sometimes savours nobly. But hear me this: Since you to non-regardance cast my faith, And that I partly know the instrument That screws me from my true place in your favour, Live you the marble-breasted tyrant still; But this your minion, whom I know you love, And whom, by heaven I swear, I tender dearly, Him will I tear out of that cruel eye, Where he sits crowned in his master's spite. Come, boy, with me; my thoughts are ripe in mischief: I'll sacrifice the lamb that I do love, To spite a raven's heart within a dove.

VIOLA

And I, most jocund, apt and willingly, To do you rest, a thousand deaths would die.

Twelfth Night - Act V Scene I - William Shakespeare

And all men kill the thing they love,
  By all let this be heard,
Some do it with a bitter look,
  Some with a flattering word,
The coward does it with a kiss,
  The brave man with a sword!

Ballad of Reading Gaol - Oscar Wilde