There are three major themes in Hardy's novel: unrequited love, catastrophe, and social hierarchy. The following is excerpt from eNotes. You can find much more detailed information on each theme by visiting the link below, but here is a sampling:
Unrequited love: Much of the plot of Far from the Madding Crowd depends on unrequited love—love by one person for another that is not mutual in that the other person does not feel love in return. The novel is driven, from the first few chapters, by Gabriel Oak’s love for Bathsheba. Once he has lost his farm, he is free to wander anywhere in search of work, but he heads to Weatherbury because it is in the direction that Bathsheba has gone. This move leads to Oak’s employment at Bathsheba’s farm, where he patiently consoles her in her troubles and supports her in tending the farm, with no sign he will ever have his love returned.
Catastrophe: This novel focuses on the way that catastrophe can occur at any time, threatening to change lives. The most obvious example occurs when Oak’s flock of sheep is destroyed by an unlikely confluence of circumstances, including an inexperienced sheep dog, a rotted rail, and a chalk pit that happens to have been dug adjacent to his land. In one night, Oak’s future as an independent farmer is destroyed, and he ends up begging just to secure the diminished position of a shepherd.
Social Hierarchy: This novel offers modern readers a clear picture of how important social position was in England in the nineteenth century and of the opportunities that existed to change class, in either direction.
Far from the Madding Crowd is a pastoral novel set in idyllic setting in a rural English village. Written by Thomas Hardy, it reflects Hardy’s affinity to tragedy, the rural life and romance. One of the most evident themes is tragedy. The tragic situations provide plenty of instances to transform the novel into a deeply touching tragedy. This is proven by the tragic ends of the three main characters of Fanny, Boldwood and Troy. The protagonist of the novel is saved from all the tragedies. Though Bathsheba faces many tragic situations, she overcomes them later
The second theme highlighted is feminism. The novel highlights the strength of the lead feminine characters, especially Bathsheba. She is shown managing a farm which is basically a man’s domain shows her individuality. Though sometimes seen as foolhardy in some of her judgments, she is seen as a woman of substance. In spite of which, Bathsheba, is seen as a character with plenty of resilience, astuteness, and fortuity to conquer her mistakes.The third theme reflected in Hardy’s Far from the Madding Crowd is the basis for a happy marriage. Hardy’s concludes that a happy marriage is based on true companionship and united by friendship and love. So, though initially we find Bathsheba’s attraction to the suave and macho Troy and a contemplation of marriage to Boldwood due to her sense of obligation, she takes the right step to marry for love and friendship which she gets from Gabriel Oak .