Definition of "heartache"

[…]: to dye, to ſleepe, / No more; and by a ſleepe, to ſay we end / The Heart-ake, and the thouſand Naturall ſhockes / That Fleſh is heyre too?

c. 1599–1602 (date written), William Shakespeare, “The Tragedie of Hamlet, Prince of Denmarke”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act III, scene i], page 265

“Well done, sister! I honour your esprit du corps. When I am a wife, I mean to be just as staunch myself; and I wish my friends in general would be so too. It would save me many a heart ache.”

1814 July, [Jane Austen], chapter V, in Mansfield Park: […], volume I, London: […] T[homas] Egerton, […], page 94

She was carrying an armful of Bibles for her class, and such was her view of life that events which produced heartache in others wrought beatific smiles upon her—an enviable result, although, in the opinion of Angel, it was obtained by a curiously unnatural sacrifice of humanity to mysticism.

1891, Thomas Hardy, chapter XL, in Tess of the d’Urbervilles: A Pure Woman Faithfully Presented […], volumes (please specify |volume=I to III), London: James R[ipley] Osgood, McIlvaine and Co., […]

Heaven knows what pains the author has been at, what bitter experiences he has endured and what heartache suffered, to give some chance reader a few hours' relaxation or to while away the tedium of a journey.

1919, W[illiam] Somerset Maugham, chapter II, in The Moon and Sixpence, [New York, N.Y.]: Grosset & Dunlap Publishers […]