It could be about secrecy. Since it's an 'untold' love story, perhaps they had to keep their relationship hidden from others for various reasons, and that secrecy was a big part of their relationship dynamic.
The main theme could be unrequited love. Maybe one of them loved the other more deeply, but it was not fully reciprocated.
Since it's an untold love story, it might be full of unspoken words and hidden emotions. Joni and Ken could have been friends first, but secretly had feelings for each other that they were afraid to express. Maybe there were some obstacles in their lives, like family differences or career pressures, that prevented them from openly admitting their love.
One possible plotline could be that Joni and Ken were childhood friends. As they grew up, they realized their feelings for each other had changed into something more romantic. But they were both shy and it took them a long time to even start talking about it.
I'm not sure who Joni and Ken are specifically in this 'untold love story'. It could be a story about two ordinary people who had a love that was never fully shared or known. Maybe they were from different backgrounds or had some obstacles in their relationship that kept their love a secret.
One possible main theme could be discovery. If two characters are in the bush, they might be discovering not only each other but also themselves in a new and natural environment.
The theme might be centered around the idea of false identities. Plagiarism involves taking on someone else's work as your own, and in a love story, this could translate to characters presenting false versions of themselves to their partners, ultimately affecting the love they share.
The main theme might be the idea of an unbreakable bond in love. 'Sticky' could imply that the love between the characters is so strong that they can't be separated easily. It could also be about the process of two people growing closer and their love becoming more and more firm, like glue that sticks things together. This kind of theme is common in love stories as it gives hope and shows the beauty of a deep and meaningful relationship.
The main character is clearly Joni. As for her friends, we can assume they play important roles too. Maybe there's a best friend among them who is always by Joni's side, someone who is really outgoing and helps Joni come out of her shell. There could also be a more serious friend who gives good advice when they face problems. But again, this is all speculation without more details about the story.
Love across distances. Since Gandia and Tokyo are quite far apart geographically, the main theme could be about how love can bridge this gap.
The main theme could be acceptance. The yetis, being different from the common perception of what is normal, find love in each other. Despite their unique and perhaps a bit scary appearance to others, they accept each other for who they are.
The main theme could be love at first sight. Since it's in a hotel, two strangers might meet suddenly and feel an instant attraction.