teenage love

My topic is on love during through highschool. I guess you could call it "Teenage love".
There are many movies that deal with love such as The Lakehouse and Serendipity and so much more.
There are a lot of relationships going on in highschool and for that period of time while the relationship is going on, both individuals are happy as ever. But when things start to go downhill whether it's your grade differences, your loved one is about to graduate, etc.., you're left with two endings. A happy ending where you remain friends and actually talk and pretend that the break up never happened, or both individuals avoid each other which ends up fooling around with their minds.
The Lakehouse and Serendipity are about 2 individuals who let time and destiny come into play to determine whether they were meant to be or not.
The Lakehouse is about a guy and a girl that live 2 years a part from each other and can only communicate through writing mail and putting it in the same mail box. The girl lived 2 years into the future and the guy lived 2 years in the past. In the beginning of the movie, the guy dies but this was in the girl's time. Every 2 years, they are able to see each other and they quickly fall inlove with each other. The first time the two meet, the girl did not notice that she was dancing and kissing the guy that has been writing to her. The guy did not tell her because in her time 2 years in the future, she had a boyfriend, but.. she didnt like him that much. Also, she might have thought he was extremely drunk or crazy. The girl finds out that it was the guy that she's been writing to that died in the car crash so she tells him and saves his life. Eventually they work around the time between them and in the end, they end up meeting each other again.
I question myself constantly thinking why do people think so much into Highschool relationships when they usually dont work out?
I know for a fact that i DO take highschool relationships seriously and not just for "experience."
Highschool relationships are not bad whatsoever. It allows individuals to be close to another person and express how they feel towards each other. Having a loved one allows an individual to feel warm, comfortable, and just able to speak their minds and be open.
What I wonder is does the love for an individual change as you get older?
For example, would loving someone in highschool say while you're 15 feel different than loving someone when you're 22?