The film's ending gets a little too gimmicky, but it's such a stunning comment on the duplicitous nature of memory. I love how the main character is trapped in this world where he will sadly repeat crimes in an attempt to achieve an ellusive closure. As far as I could make out, the couple that he talks about were just figments of his own imagination. My review of the film can be found on my site:

http://www.slantmagazine.com/film/archive/memento.html