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It's worth noting that the evolution of this phrase is an excellent example of how language and idioms can change over time, shifting from literal to metaphorical meanings.

The exact timing of when this phrase became a metaphor for falling in love is not precisely stated in the search results. However, it's clear that by the late 19th century, the metaphorical usage was becoming established. The phrase "head over heels in love" is noted as being in use from the "late C. 19–20" (late 19th to 20th centuries)6.

The metaphorical usage of "head over heels" to describe falling in love emerged later. By the late 19th to early 20th century, the phrase had evolved to mean "madly in love" or "very much in love"67. This shift in meaning represents a significant change from Stevenson's literal usage.

The cliche meaning of "head over heels" has indeed changed since Robert Louis Stevenson used it in its literal physical sense.
In Stevenson's short story, the phrase "head over heels" was used to describe a physical action during an altercation: "At the same moment I knocked him head over heels"5. This usage reflects the literal meaning of someone being flipped upside down.

has the cliche meaning of "head over heels" changed since Stevenson write the phrase in a short story using it in its literal physical meaning describing an altercation? when did the usage of this phrase become a metaphor for falling in love?
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