He says in a footnote – I love books with good footnotes – that the Oxford English Dictionary hyphenates light-hearted, but “on the same page heartbreaking appears as one word, while heart-rending and heart-stopping both have hyphens”.

Is heartbreak one word or two?

crushed with sorrow or grief.

How do you use the word heartbreaking?

Examples of heartbreaking in a Sentence

She wrote a heartbreaking story about the death of her grandfather. It was heartbreaking to know that there was nothing I could do. The team suffered another heartbreaking defeat.