Whatever the catalyst, crushes are fun and awful and sometimes dangerous. And they are always a factor in Young Adult Fiction, because they are always a factor in the lives of young adults.
Even if the characters live in a post-apocalyptic hell and are fighting for their lives, they are going to be consumed with thoughts of their crush or crushes or confusion because they did like one person but ever since the chemical explosion, those feelings have changed.
It reminds me of the beginning of Eat, Pray, Love Julia Roberts talks about refugees who once given an opportunity to talk to a therapist they didn't talk about their plight, they talked about crushes and love and relationships. It's our nature.
I found this website, Letter to Crushes, it is exactly what it sounds like. People post letters to and about their crush. It's adorable, time consuming, awkward and fun. Most of all, if you are a YA writer you don't have to feel bad if you spend an hour perusing the entries, call it research. The majority of posts are written by teens.
Below are a few of my favorite entries from the website. The pictures are my addition.
You look hot in glasses.
Eye contact is pretty damn exhilarating.
For the writers
I love you more than a grammatically correct sentence.
I certainly hope kissing is allowed in libraries.