Tolstoy's "Anna Karenina" is the story of a passionate love affair that ends in suicide.

But it also reveals the dark reason behind why people cheat — and how to avoid doing so yourself.

Here's what her tragic story can teach you… 

Anna Karenina is a rich aristocrat trapped in a loveless marriage

Her husband is kind, but career-driven. He often neglects Anna, and she finds him boring

Anna grows increasingly sad and lonely — until she meets a man at a train station…

The man she meets is a young cavalry officer named Vronsky

He’s charismatic and loved by all the ladies — but he soon desires Anna

Vronsky’s passion brings Anna a sense of joy and excitement she hasn’t felt in years

She begins an affair with him, and things turn for the worse

Scandal breaks out when Vronsky impregnates her

Though Anna’s husband forgives her, Anna refuses to stop cheating

Instead, she elopes with Vronsky — abandoning her family and her children

Unfortunately, the two lovers will soon discover just how shallow their “love” is…

The scandal brings great shame to Anna

Friends, family, and society turn on her for betraying her family

She’s forced into social exile — unable to leave her house without being mocked

Lonely and outcast, she begins clinging to Vronsky

Vronsky, meanwhile, discovers that Anna’s love doesn’t make him happy

He’s ashamed that he ruined her marriage, and grows repulsed by her clinginess

He grows distant, and Anna feels herself losing the only man who won’t reject her

From here, things begin to spiral…

Anna turns to drugs to numb her loneliness

Jealousy, paranoia, and rage consume her

She begins to hate Vronsky, convinced he’s cheating on her and about to leave

Finally, the pair have a fight, and Anna believes she’s lost Vronsky — all she had to live for — for good…

Driven insane by the fallout from her affair, Anna throws herself under a moving train

Her death is graphic — but her downfall has been immortalized for other reasons

Specifically, Anna’s tale is a universal warning against adultery…

Tolstoy doesn’t simply warn that adultery is bad

He warns that adultery — and all marital discontent — is preceded by a dereliction of duty:

A marriage doesn’t fall apart when it becomes unhappy…

It falls apart when spouses forget the commitment they made to love each other

Anna’s affair was entirely selfish — her main concern was “how can I be happy?”

She never considered her husband or her children

Tolstoy asserts that by ignoring her duty to her family, Anna led them all to disaster

So what does he say you should do in an unhappy marriage?

Tolstoy’s solution is simple — do your duty.

Uphold the vows you made to love and serve your family, even when it seems fruitless

Ultimately, Tolstoy says, a meaningful life is built by you fulfilling your duty

Not by chasing your own personal happiness…

All of this is summed up in the opening line of Anna Karenina:

“Happy families are all alike; every unhappy family is unhappy in its own way.”

But why are all happy families alike?

Because they’re all characterized by one principle — adherence to duty

It is precisely by adhering to your vows — especially when you least want to — that true love is shown

Lasting relationships are built on this sense of duty, of living up to your vows no matter what

And they’re destroyed by failing to do just that