Hector Berlioz (1803 - 1869) was a French classical composer of the 'romantic' period. He wrote Symphonie Fantastique after he fell in love with an Irish actress who he eventually married but the marraige was ultimately unsuccessful.
It is thought Berlioz wrote the last movement of the Symphony when high on opium and you can find the full symphony here which is performed by the Detroit Symphony conducted by Leonard Slatkin.
The track below from the symphony is the 2nd movement entitiled 'Un bal' (A ball) and is a waltz performed by the Philharmonia Orchestra conducted by André Cluytens.
Berlioz said the whole piece was intended to be in the imagination of an artist under the influence of opium who was in the depths of despair because of hopeless, unrequited love. A state of mind he himself was in at the time.
Hector Berlioz discography can be found here.