For a three-act plot analysis, put on your screenwriter’s hat. Moviemakers know the formula well: at the end of Act One, the main character is drawn in completely to a conflict. During Act Two, she is farthest away from her goals. At the end of Act Three, the story is resolved.
Act I
The first third of this book lays the groundwork for the two most important characters: Gabriel Oak and Bathsheba Everdene. We find out in these sections that Oak is a responsible guy whose modesty can sometimes get the best of him. Oak proposes to Bathsheba and she says, "Naww, you're not good enough for me."
Things also go (additionally) horribly wrong for him when all his sheep die and he has to sell off everything he owns to pay his debts. Bathsheba has the opposite fortune: she inherits her uncle's farm and becomes rich.
Act II
Oak becomes a reliable servant to Bathsheba, but also a good friend who will tell her the truth even when she doesn't want to hear it. A dude named Farmer Boldwood does his best to marry Bathsheba, but it's pretty clear from the outset that this old, boring dude isn't going to succeed, no matter how pushy he is with his proposals.
Enter Frank Troy, who is a hottie with noble blood running in his veins. Bathsheba is a smitten kitten, and the two crazy kids get hitched. Too bad Troy is a drunk and a scumbag and—oh, yeah—is sending money to his baby mama Fanny Robin.
Things go pretty crazy when Fanny Robin (and her baby) dies, and Bathsheba finds out about Troy's past. Troy tells Bathsheba that he only ever really loved Fanny (which: seriously? You left her to die in the poorhouse, bro), and decides to skip town and fake his death.
Act III
With Troy out of the picture, Farmer Boldwood decides to live up to his name and act boldly. He hounds Bathsheba about marrying him until she basically surrenders out of total exhaustion. Boldwood plans on announcing their engagement at a Christmas party he's hosting, but at the last second, Troy comes back to claim his wife. It turns out that he hasn't much liked living without her money.
Boldwood goes ape when Sergeant Troy steals Bathsheba (again), so he takes out a shotgun and shoots Troy. When the doctor shows up, Troy is dead. Boldwood, in the meantime, has turned himself in at a nearby police station. He is originally sentenced to be executed, but is pardoned at the last second because the court has found him insane. He's still going to spend the rest of his life in jail, though.
With Sergeant Troy and Farmer Boldwood both out of the picture, Gabriel Oak and Bathsheba decide to get married. Bathsheba is okay with this marriage because Oak is a) not a sleazeball with a secret baby mama b) not an insane trigger-happy weirdo and c) newly rich. Good deal.