Life is random. Fiction is not.
This is called "plot".
The basic rule of (most, regular) fiction is that everything that goes on in the narration must somehow relate to the protagonist and his goals. You do not fill your story will irrelavant details or randomly string together people and events that lead nowhere.
In life, things might happen that have no relation to what you are on about. For example, a husband might try to save his wife from a kidnapper and get run over by a drunk diver. End of story. In a novel, this would make the readers throw away the book and never buy anything by that author again. In fiction, the husband must battle the kidnapper, not the randomness of the world.
The reason for this is that we do not experience life as random. We look back on our lives and see how everything appears to have happened to lead us just to this moment. Richard Feynman uses this perception to illustrate the fallacy of a posteriori conclusions:
You know, the most amazing thing happened to me tonight. I was coming here, on the way to the lecture, and I came in through the parking lot. And you won’t believe what happened. I saw a car with the license plate ARW 357. Can you imagine? Of all the millions of license plates in the state, what was the chance that I would see that particular one tonight? Amazing!
Fate is how we feel about our lives, and fiction – which is usually told in the mode of looking back on events and attempting to make sense of them – does just that: make sense of randomness.
Of course there is experimental fiction that breaks the basic rule of having a coherent plot and plays with the reader's expectation, but even this fiction only works before the background of that convention.