Lady in Red.

A little history

"Lady in Red" is a song by Chris De Burgh. It went to #1 in 25 countries.
The song is about his wife Diane De Burgh.
It was released in 1986 on the album "Into The Light" and peaked on the Billboard charts at #3 in 1987.

The song appears briefly in the 2000 film adaptation of American Psycho when Patrick Bateman, played by Christian Bale, is listening to it in his office on his walkman.

Info courtesy of: http://www.wikipedia.org/