Should Light Hearted Be Hyphenated?

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 it light-hearted or light-hearted?

Someone who is lighthearted is cheerful and happy. I was amazingly lighthearted and peaceful. Something that is lighthearted is intended to be entertaining or amusing, and not at all serious.

Is light-hearted a compound word?

“Light-headed” and “lighthearted” will get you every time. ... Most other words involving “light” are open, as in “light pen;” the exceptions are “light-headed” and “light-rail.” When the word “light” is the last element in a compound, it's spelled solid. Examples: flashlight, candlelight, etc.