Thomas Hardy's novel, like the majority of mid-Victorian novels was first published in serial format in the magazine Graphic in 1884-5 and then in double-decker format. Thus we have two versions of the novel and two different audiences.
The initial publication is serial format accounts for much of the chapter structure of this, and most other serialized, Victorian novels. Since the object was to persuade the reader to continue to buy issues of the magazine (or to subscribe), chapters end on a mystery or a note of suspense.
Novels, after their serial runs were complete, would next be republished in hardcover, normally in triple-decker (3 volume) format, a tradition that is strong through the mid-Victorian period, but as reflected in the double-decker publication of Hardy and Marie Corelli's pioneering initial single volume releases, was losing traction by the fin-de-siecle.
Hardcover multi-volume editions were intended for sale to circulating libraries (most notably, Mudie's). Individuals paid for subscriptions to libraries and selected volumes of a monthly list that the libraries shipped to them in the mail, and which were to be returned at the end of the month.
The audiences for both the formats were often female, but not always, and from the middle and upper middle classes primarily.