A borrowing from French, the phrase amour fou, literally mad love, denotes uncontrollable or obsessive passion or infatuation. It was introduced into English as a theme of drama, prose narrative and cinema.

In French, the phrase occurs, for example, in Les Amours d’un interne (Paris: E. Dentu, 1881), by the French author Jules Claretie (1840-1913):

— Alors, dit-elle vivement, en posant sa petite main fine, dont Pedro sentit la pression nerveuse, sur le bras du jeune homme, vous venez ici pour me parler d’amour ?
— D’amour, oui ! D’un amour profond, d’un amour fou !… Depuis que je vous ai vue, Olga, depuis que vous m’êtes apparue, je vous aime, je vis avec votre pensée et votre image !
     translation:
— So, she said livelily, putting her fine little hand, of which Pedro could feel the nervous pressure, on the young man’s arm, you’re coming here to talk about love?
— About love, yes! About a profound love, a mad love!… Since I saw you, Olga, since you appeared to me, I’ve been loving you, I’ve been living with the thought of you and the image of you!

The first mentions of the French phrase in English refer to L’Amour fou ou La Première surprise, the title of a comedy by the French playwright André Roussin (1911-1987), first produced at the Théâtre de la Madeleine (Paris, France) on 24^th September 1955:

– In British English: The following, for example, is from the column Priscilla in Paris, published in The Tatler and Bystander (London, England) of 19^th October 1955:

M. André Roussin, of The Little Hut fame, and so many other gay triumphs, has done it again. After having been tried out and run in at Brussels, his new comedy L’Amour Fou has had a brilliant Paris première at the Théâtre de la Madeleine. The way this young dramatist manages to get away with situations that—if they were taken seriously—would make one feel somewhat uncomfortable is hilariously miraculous.

– In American English: The following by Preston Grover, of the Associated Press, was published on 12^th October 1955 in many U.S. newspapers—for example in The Terre Haute Tribune (Terre Haute, Indiana):

Paris, Oct. 12.—(AP)—[…] The Paris theater season is booming, having started off with “L’Amour Fou” (Mad With Love), the comic story of a high-level man falling for a second-level dame.

The phrase then occurs in Fete (New York: Albert A. Knopf, Inc., 1961), the translation by Peter Wiles of La Fête (Paris: Gallimard, 1960), a novel by the French author Roger Vailland (1907-1965)—this is an extract from Fete:

“I’d like l’amour fou.”
“That’s all right by me,” said Léone, “if it’s useful to you. I hope you will find l’amour fou. But you don’t believe in it.”

The reviewers of Fete mentioned the phrase—for example Andre Michalopoulos in The Light (San Antonio, Texas) of 29^th January 1961:

Fete is an expression used by Duc, a novelist who is the protagonist in the story, to describe any experience deliberately pursued for the state of enthusiastic euphoria which it is expected to induce.
It can be a wild love affair, the amour fou which is the subject of the novel he is unsuccessfully trying to write and which he abandons in favor of the amour fou he is himself engaging upon in real life.

The phrase may have been further popularised by:
– the fact that the U.S. playwright, screenwriter and translator Ruth Goetz (1908-2001) translated and adapted Roussin’s L’Amour fou as Madly in Love, which opened on 5^th August 1963 at Playhouse in the Park, in Philadelphia, Pennsylvania;
– L’Amour Fou (1969), by the French film director Jacques Rivette (1928-2016), which was released in Canada in 1969 and in the USA in 1972.

The earliest occurrence that I have found of the phrase used in English without explicit reference to French is as the title of the following piece by the British poet Christopher Middleton (1926-2015), published in The Observer (London, England) of 31^st March 1963:

AMOUR FOU

The hand taking the hand holds
nothing   And look   The trouble
with two sets of eyes
is that each wants out.

Islands. But we float, if face
to face we sit down in bars,
our space acquires us,
orphans of blue dust

There is a call for help, milking
an older silence that can give suck.
Me I shall not resist.
An owl should adore the empty air.

So make your body from the heap
of shadows down my mind. Nothing’s there
for you to resist. Today, dear house,
you’ve got not a thing that’s mine.

Mirrors—not needed, we
are detached otherwise.
Chairs and shoes, our
dependents—gone.

To the call, the one perplexed
voice calling replied
less and less. Darkening our room,
these are the mountains we roll

The second-earliest occurrence that I have found of an English use of the phrase is from the review of Elvira Madigan (1967), by the Swedish film director Bo Widerberg (1930-1997), published in The Sydney Morning Herald (Sydney, New South Wales) of Saturday 8^th June 1968:

GALA CINEMA: CURRENT and COMING SHOWS:
[…]
ON FRIDAY: “ELVIRA MADIGAN”
Exclusive Australian premiere season at GALA CINEMA of BO WIDERBERG’S Cannes award winner—the brilliant EASTMANCOLOUR production of an historic Swedish “L’Amour Fou”—a young count who deserted his family and regiment for one summer of unheeding love with a beautiful Circus tightrope star.

Tom Milne used the phrase in the review of King, Queen, Knave (1972), by the Polish film director Jerzy Skolimowski (born 1938), published in The Observer (London, England) of 28^th October 1973:

Basically, it is a triangle situation with puckish overtones of obsession and perversion. A wealthy businessman (David Niven) and his luscious wife (Gina Lollobrigida) assume responsibility for an orphaned nephew (John Moulder-Brown); and while he hopefully trains the impossibly clumsy interloper as a son, she indoctrinates him as an orgiastic lover. Lovely interventions by a crazy German scientist who has invented an artificial skin of great erotic potential; a plot escalating through amour fou into impulsions to murder; and a fair sprinkling of fine visual gags beautifully played by all three principals. It drags here and there, admittedly, but it is genuine Skolimowski.