Things wrong with that scene:
1. They don't look like high school kids.
2. People wouldn't be crowded around the two people, hanging on every word like that.
3. High School parties like this only exist in the movies.
4. Not funny, not even a little bit.
5. So she finds the letter and suddenly they have a budding romance, even though they hardly know each other and are going off to different school where they will meet other people.
6. A letter? A letter makes her fall for him?
7. The police would have been called 30 minutes into this high school party.