Part I of the novel does most of the work of setting up the initial situation for us. We learn about the host of factors that contribute to Antoinette's unstable childhood. With her father dead and her family's finances in shambles, Antoinette and her family occupy a kind of no-man's-land in Jamaican society. Shunned by both whites and blacks, they make do for a couple of years until Annette realizes one day that she doesn't have the resources to raise her children well. So she has to provide for them in the only way she can as a white Creole woman – get hitched to someone rich and white. Enter Mr. Mason. But instead of giving her family security, her marriage with Mr. Mason ends up costing Annette her home, her son, her sanity – and her life. Annette's tragic experience is, for Antoinette, a legacy of insecurity and deep skepticism – really, fear – of society and of love, of her sexuality and her sense of self.
We know it's odd to describe a marriage as a conflict, but in Antoinette's turbulent world, marriage is an incredibly fraught thing. Marriage isn't a union of two people in love, but a financial arrangement manufactured by her stepfather and her stepbrother. Instead of insuring her security, her apparently well-intentioned stepfather's goal, Antoinette's wealth is signed over to Rochester, thus resulting in her loss of economic freedom. To be fair, Rochester in the beginning seems to have some genuine feeling for Antoinette – remember the part where he promises to trust her if she trusts him? But whether this promise can withstand all the baggage they bring into the relationship…well, that's why their marriage is a conflict.
Even though Daniel's letter is filled with all kinds of spiteful, self-aggrandizing comments that inspire skepticism in the reader, it preys on all of Rochester's insecurities. The fact that Antoinette's family might have a history of madness and degeneration brings out his ugly racial prejudices about Antoinette's being a white Creole. The fact that Antoinette might have had a relationship with Sandi Cosway brings out his own shame about having to marry someone for money and not for love, a luxury only the eldest son in the family can afford. Rochester isn't enraged after he receives the letter; he feels like it's saying something he already knows precisely because it plays on his insecurities. He doesn't really give Antoinette a chance to defend herself. From this point on, their course of their relationship has irrevocably changed.
Yes, we realize that there is a sexual climax at the climax of this novel. In the novel, sex isn't just a physical act, but a battleground on which all of the forces that shape the characters collide; orgasm isn't just a physical consummation, but an assertion of power of one will over another. When Rochester ingests the obeah powder, he sleeps with Antoinette, but he's also rendered into a virtual zombie: he loses his will, his reason, his identity, the very feeling of being a live, sentient human being. He punishes Antoinette by sleeping with Amélie, who has openly mocked Antoinette for being a "white cockroach." Rochester's infidelity absolutely destroys Antoinette and her hopes for happiness.
The climax, or climaxes, of the novel generate(s) a series of reactions that worsen the situation. Instead of talking things over reasonably, everyone – Antoinette, Rochester, and to a lesser degree Christophine – seems to feed off each other's volatile emotions until they become lost in a blazing mess of acrimony. In such a state, neither Antoinette nor Rochester seems able to distinguish love from hate, and they both alternate between fiery rage and icy calm. It's difficult to know who to believe or who to sympathize with at this point.
Rochester has Antoinette declared insane, ships her back to England, and locks her up in his attic. Confining her in this way is really only finishing off geographically what he's done to her on a physical and emotional level. Having already appropriated her fortune, he now lays claim to her entire person, symbolically indicated by the fact that he re-names her "Bertha." In Part III, Antoinette's narrative reflects this loss of self through her constant questioning of who and where she is.
While it may seem that the novel concludes with Antoinette's setting fire to Thornfield Hall, technically it's only in her dream where she sets fire to the house. The novel actually ends with Antoinette waking up from her dream and walking down a "dark passage." It's true that she says that she finally knows what she has to do, but she never specifies what this mysterious task is. For a fuller discussion of the ending, see our "What's Up with the Ending?" But let's just note here that the open-endedness of the ending seems fitting for a novel that has been driven by conflicting perspectives, a novel that has never given us readers the "truth" of what happened from an impartial or omniscient point of view. No one in the novel is exempt from its relentless perspectival clashing, not even the seemingly cool and calculating Rochester, and the novel isn't about to let us off the hook either.