I was fourteen when I first read Hosseini's novel, A Thousand Splendid Suns, and many of its scenes have been sharply embedded in my mind ever since.

A book title can be written like this, or in italics, or with " ". Whichever you like best!

It is an unbearaincredibly poignant story and the first book that sparked my interest in literature.

Unbearably is usually negative, as in the entire book was negative.

I shared the ordeals his characters faced and felt their desolation and hopelessness.

His stories are directed by events that feature those themes, and every event is an instance of human fortitude and preoccupation with survival during violent, tortured, and agonizeding moments.

Love, despite its intrinsic beauty and power, is too susceptible to extrinsic environmental factors; it is therefore too precarious and too agonizing to bear in the war-ravaged landscape of Afghanistan.

Delete, copy

I believe it is his intransigent belief in humanity that makes his stories universally appealing.

Delete, copy

ItThe story is an unbearably poignant story and the first book thatand it was the novel to sparked my interest in literature.

Nothing wrong with what you wrote, just giving an alternative! Nicer to use more specific vocab like "novel" when possible (but you already do this elsewhere!)

Hosseini's writing is simple but loaded, yet overflowing with sensory details and graphic war descriptions, giving the reader the sense of being physically present in Afghanistan and eliciting their sorrow and sympathy.

small changes! Good vocab overall

Year by year and book by bookTime and time again, I have read his words, every time held in complete awe and admiration for their beauty, content, and truth.

I like your original, but I do think that the "year by year" and "book by book" are a bit clunky/repetitive. It's VERY emphatic, which could be your intention, so I made it a bit less so.

With his emotionally lacerating depiction of the characters' predicaments, I could feel a growing sense of anxiety gnawinged away at my stomach as I read his stories.

His vision is always focused on humanity—the fundamentals of human nature, the problems, and aspects of characteristics that apply to any age and any countryre universal.

Again, just a precise word choice that sums up what you wanted to say , though there was nothing incorrect in your original sentence.

War, destruction, violence, and despair are common background elements in Hosseini's novels, whereCommon background elements in Hosseini's novel include war, destruction, violence and despair, while themes such as humanity, faith, hope, and salvation are thestand out prominent themesly against this backdrop.

Not a correction, just an alternative.

His stories are directed by events that feature the theme, and everya series of events, where each event is an instance of human fortitude and preoccupation with survival during violent, tortured, agonized moments, demonstrating the key themes.

every = more generalised, like all the events each = every specific individual event

The omniprescence of death during wartime turns it into a potentially destructiveis weaponised, putting the characters through the anguish of departure and separation.

I'm not sure what you're referring to with "it"?