Belly Conklin feels things very deeply.

Caught between her affection for two boys – brothers Jeremiah and Conrad – she dreams about them both, the futures they could have, the kisses they would share.

Lara Jean Covey feels things very deeply.

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She writes letters to boys she forms a connection to, even if they don’t know she exists, until her secret missives make their way to the addressees, and one of them, Peter Kavinsky, approaches her with the piece of paper in hand.

Jenny Han is the woman behind both those stories, The Summer I Turned Pretty and To All the Boys I’ve Loved Before, young adult fiction books that have turned into streaming sensations, on Prime Video and Netflix, respectively.

Those stories capture a special moment in a young girl’s life, when they start to awaken to the fantasies and possibilities of love. It’s a heady time when every stolen glance at a crush could end up in red-cheeked embarrassment or ultimate wish-fulfilment (or, more likely, nothing at all).

Almost everyone goes through it, but teen girls go through it with so much emotion and angst, right there on the surface. The complexities of reality and adult responsibility has not yet hit, and the rush of hormones makes everything heightened. The highs are euphoric.

“There’s something very magical about girlhood, and growing up and experiencing life for the first time. It all just feels much more potent and intense,” Han told The Nightly.

Han is in Australia this week to promote the release of The Summer I Turned Pretty’s third season, which after one week, has been watched by 25 million viewers around the world, according to stats provided by Prime.

That’s a lot of people swooning to the dramatic turns in Belly Conklin’s (Lola Tung) life as she enters the final year of university and re-examines a question she thought she had settled.

The Summer I Turned Pretty is breezy and sweet, and very popular among young women who see in its recognisable character types aspects of their own teenage years.

Han, 44, wrote her first novel, Shug, while she was still a teenager in university. On the cusp of adulthood, she still felt closer to her 12-year-old protagonist than she did to grown-ups whose experiences she had not yet lived.

The Summer I Turned Pretty trilogy followed, then the Burn books and the To All the Boys series. To All the Boys was the first to be adapted for screen with a very well-reviewed Netflix film released in 2018. It had the tenderness of a throwback teen romance with the freshness of the modern era. It was earnest and wholesome.

Han was already a big name in young adult literature and now the streamers really wanted in. To All the Boys had two sequels and then a spin-off series, XO, Kitty.

When she started to develop The Summer I Turned Pretty with Prime, she also came on as creator and showrunner, an unusual move for an author who generally relinquishes control to the studio. But Prime recognised that it was Han’s sensibility that earnt her loyalty from her fans.

Despite being almost three decades older than her characters, Han still feels connected to the younger generation by not viewing them as some kind of scary alien species that either need to be patronised or diminished. Han’s work validates them.

“In general, women’s experiences aren’t perceived as equal because (it’s seen) as not a human experience, it’s just a woman’s experience.

“In the same way that people will minimise artists that women enjoy, and people will think it’s not as serious. If a song is about heartbreak or love, people think that’s not serious. I don’t know what’s more serious than that.

“When you look back at your life, what was really important? What are the things that defined you? I don’t think it’s going to be how much money you made or how successful you were. It’s going to be those relationships and the people that you loved.

“Even when you’re watching a movie about war or death, the things that move people are stories about love.

“The part of the story I really care about when I’m watching The Hunger Games is Peeta and Katniss. Yes, I care about the resistance and I care about everything else, but what keeps you going is you’re hoping that they’ll find a way.”

A young person’s experience is a human experience, you just have to be open to their significance.

For Han, she wants to be respectful to the enormity of what a teenage girl is feeling, even if you know, as an adult, that those seemingly disproportionate moments are not as massive as it feels in the moment. That’s her guiding light when it comes to girlhood.

She talks to the young actors on The Summer I Turned Pretty, Tung and Rain Spencer, but she also has friends who are older. The women in her life teach Han something about what’s it like to be a girl at any age – and she’s listening.

Let’s hear it for the girl.

The Summer I Turned Pretty is streaming on Prime