For those of you who read Tristram Shandy, maybe you can give some insight to this. I was curious why Jennie (the runner, not the girlfriend) never changed her clothes throughout the film. All the other characters changed, so why not her? Was it supposed to be a comment on time passage? In relation to the clock winding or something? Is she supposed to be a static character who never changes, so therefore she did not 'change' literally? Maybe she represents immature love, that is ill-developed, because he's pretty much cheating on his girlfriend while she is home taking care of his baby. Perhaps the message is that sleazy promiscuous passion is incapable of maturity or growth.
Maybe they never changed her outfit because, though she had a bigger role in the film (who doesn't like a bit of scandal?), they wanted us to know that she's not a terribly important character in the book (In fact, niether Jennies seem to have been). Whereas the wardrobe of the main characters was a ridiculously big deal...