Now some would say structure must be the same in all books but I disagree. I think there are always exceptions; but with any of the creative arts, it's good to know why something is done before you break a rule.
A novel is like a symphony in that its closing movement echoes and resounds with all that has gone before. . . . Toward the close of a novel. . . . unexpected connections begin to surface; hidden causes become plain; life becomes, however briefly and unstably, organized; the universe reveals itself, if only for the moment, as inexorably moral; the outcome of the various characters' actions is at last manifest; and we see the responsibility of free will. John Gardner
Nigel Watts in his book, Writing a Novel and Getting Published, called this beginning period stasis. It is basically everyday life before a gatekeeper experience changes everything. Call it gatekeeper or trigger, something has to happen to take this person from their life as they have known it.
The something is the point of the novel whether that is an idea, an event, a quirk in their personality. This is where the character takes off on the quest, which might happen right in their own backyard or take them to a fantasy land.
Here is where things happen that cannot be expected by the character or the reader-- the surprises, the uncertainties, the twists, turns, obstacles, conflicts. Here is where the WwW is brought into action, with mini-climaxes. These happenings may relate to the initial quest or not. These events may come out of the setting, other people or the character's own development.
In a love story this could be personalities, events, goals, or outside competition. Sometimes the characters have a common goal that until it's been resolved, they cannot work things out to be together. The action usually comes out of the nature of the problem or their character although once in awhile something comes along which can be unexpected with no foreshadowing-- sort of like a tsunami in life.
At some point, nearly the climax, the characters must make an important, life changing choice. If they make the wrong choice, it can turn tragic. Villains make these choices also.
The final climax is where it plays out in a way rewarding to readers and characters. Rewards and final battles are fought. Ideally the last battle, as in Lord of the Rings, relates to the original quest.
Finally there is the return home where the character has been changed by the experience, is wiser, and whether the character leaves their original home or returns, this is where it make sense to leave the story.
Nigel Watts, in the book mentioned above, referred to these eight points as: stasis; trigger; quest; surprise; critical choice; climax; reversal; resolution. Whatever they are called, they are the structure of most novels.
One thing I like in my writing is have something that appears to be the problem, the thing that throws the protagonist from their world, but it's usually not all it really seems. The story is actually told on two levels. One might be obvious-- bad guy versus good guy, good fighting evil.
The second is not obvious and my hope is readers will get this one eventually if not when they read the book. It's the deeper meaning that matters most to me. Not to say it won't be linked to the surface issue, but it's not the real essence. Understanding this deeper level is not needed to enjoy my books or favorite stories, but when it is understood, I think it leaves a satisfying life lesson.
We recently watched The Magic of Belle Isle starring Morgan Freeman as a writer who has lost the excitement of writing. I had seen it before and loved it but forgotten how well it illustrates these dual levels. It is a good example of how the surface isn't all a story is about. As to what are the two levels in that film, watch it and I think you will find it obvious.