Looking for Alaska
By John Green
The protagonists are Miles "Pudge" Halter, Chip "The Colonel" Martin, and Alaska Young.
There's no true antagonist, since many characters who opposed the protagonist later would also support them, but the argument can be made that the protagonists are their own enemy.
Just as Pudge Halter's life is seemingly at its greatest, tragedy strikes, leaving Pudge and his friends reeling with unanswered questions.
"You spend your whole life stuck in the labyrinth, thinking about how you’ll escape it one day, and how awesome it will be, and imagining that future keeps you going, but you never do it. You just use the future to escape the present." - Alaska Young
The main themes of "Looking for Alaska" are coming of age is a difficult process, sacrifice is a part of love, and coming to terms with death.
I would recommend the book to anyone who wants to read a thought-provoking, emotional, coming-of-age story about dealing with tragedy.