I recently watched this film, and it stayed with me for days. And in addition to the melancholic characters and their highly sexual chemistry, the music really stuck with me.
It's scored by an old group called Shudder to Think. The mostly-instrumental tracks are ambient, with lots of synth pads, moog bass, reverb-heavy downtempo beats, and this distinctly-90s-production-value sound. I don't know how to describe it... maybe like Buddha Bar, except not totally lame? Chill out? I dunno. They're not all winners, but some of the tracks - like That's Fat - are pretty great.
Give it a try.