It's a theme without ending so the ideal incidental music would be without resolution. Indeed, it could be done with two endings as in The French Lieutenant's Woman, with parallel but different alternative endings if employing a Pinteresque screenplay. Then we could have a prequel (Jane Eyre / Wild Sargasso Sea stylee), portraying the downfall of the d'Urbevilles . . . which reminds me, I've just got the irony of Tess reciting that Shelley poem Ozymandias . . .