The thing I like most about Science Fiction is the genre's ability to cross the line in the realm of fantasy, with no worry about the fantasy being deemed impossible. Using some sources mentioned in this thread, I've been searching for origins of the concept, "Fantasy Wife". My ideal wife would be Bridget Bardot, circa 1965, without all the politics.
First we have Fritz Leiber's story, Mechanical Bride (1954):
http://www.technovelgy.com/ct/content.asp?Bnum=1041
An excerpt from the story is quoted on the site:
"...Men don't want real women anymore. You and I are behind the times, Chernik. We still believe in love. But most men just want beautiful, brainless robots. That's all my man really wanted. He didn't want me to have a will of my own. He didn't want me to be alive..."
Sorry, I can't point you to sources for the full story, since the Leiber collection is oop.
Next, we have Richard Matheson's teleplay for Twilight Zone (1960):
http://www.imdb.com/title/tt0734553/
In "A World of His Own", author/character Gregory West conjures up dream women with his typewriter. How intriguing. When I was a young boy, I thought Victoria West, the author's wife, who was portrayed by Phyllis Kirk, was a foxy b*tch. This tale has a twist, so it is best just to rent the episode on dvd.
A decade or so later, we have Ira Levin's, The Stepford Wives (1972). This book needs no introduction, since most of you have either read it, or seen the movie(s).
Well, we see a recurring theme, and clearly in later years, there are probably more examples of stories involving the fantasy wife or mistress. However, is there anything that precedes Leiber's story?

One last request. What was the first SF story that dealt with the breast implant? This abomination is one of man's worst inventions! I'd like to go back in time and eliminate the man who first thought of the idea.