Our love? Only for half a day (5)

I believe the answer is:

amour

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'day' is the definition.
The definition and answer can be both states of affairs as well as being singular nouns.
Maybe there's an association between them I don't understand?

I can't explain the remainder of the clue.

Can you help me to learn more?

(Other definitions for amour that I've seen before include "Illicit love" , "close relationship" , "Sexual liaison" , "Secretive affair" , "Affair of the heart" .)

I've seen this clue in the Evening Standard.

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