In early 1947, the French philosopher Simone de Beauvoir traveled across the United States. During her four-month voyage she met and fell in love with the then quite famous American novelist Nelson Algren of Chicago. At the time both were in their late thirties. When she had returned to France, she wrote Algren that she had put aside the project she had begun prior to her departure for America ( The Other Sex , 1949) and undertaken to write a book about the New World, for something [had] happened [...] and it was the beginning of love. The journey, she continued, for this reason had to be preserved. Apparently, the passion she had experienced with Algren (it is said that with him she enjoyed sex for the first time in her life), above all had an impact on her primary occupation in life: her writing. In my paper, I look at how de Beauvoir reflected on her affair with Algren in three different works, i.e. her America Day by Day (1947), her novel Les mandarins (1954), and the third volume of her memoirs (1963). All three books were written at different stages of the relationship, and therefore offer quite diverse perspectives that taken together add up to a more comprehensive picture of the affair. When writing America Day by Day , de Beauvoir was deeply in love, and Algren returned this feeling. Yet, Algren does not appear as a predominant figure in the book he inspired; he is hardly mentioned. For, de Beauvoir thought that once she wrote about someone or something, it was lost to her. She consequently had to find a way to write about him-he preoccupied her mind-without actually writing about him. She succeeded in doing so by writing about his America, i.e. the places he showed her. Whatever she sees fascinates her. In fact, this fascination reflects her admiration of Algren rather than of America. By 1954, the romantic phase of the affair was over; a first rupture had occurred. In the novel, de Beauvoir's alter ego Anne from the beginning sees that the affair is doomed to fail. There is a life before and after the trip to America. Both lovers' inability to give up their previous life for a mutual future is a hovering threat from the moment they first lay eyes on one another. During her trip to America Anne looks at Lewis the person directly rather than to convey an emotional but indirect portrait of him by means of describing his surroundings. By the time de Beauvoir published the third volume of her memoirs in 1963, she claimed that all feelings for Algren had died. The few paragraphs dealing with him are written from great distance. In facts, she concentrates on the long and dangerous passages to and from America rather than to write about him. Her infatuation with the American writer is likened to a nervous condition possibly to be remedied with medication. As a prior reason for the relationship to start, she indicates her (masculine) desire for a short sexual adventure in America. Little surprisingly, Algren broke with her for good after he had read the hateful book. Nonetheless, his memory of her was alive until his last interview shortly before his death some twenty years later. De Beauvoir in turn, though she was buried next to Sartre, had wished to be buried wearing the ring Algren had given her once upon a time, and so it was done. As one critic observed, in the end, she was more comfortable with sex in the head than with sex in bed.