One thing in particular I've noticed about teenage girls: It's all about the romance.
The progression every few months goes like this:
Teen 1: "I'm fine on my own, don't need a man to make me happy! Life is goooood!"
Teen 2 response: "I'm so happy for you, you go girl! You don't need anyone."
Teen 3 response: "That's right, girl, we don't need nobody."
A month or so later:
Teen 1: "He makes me so happy, I've never felt so good. I don't know how I'd live without him! <3 [boy's initials]
Teen 2 response: "Awww, that's so sweet. You'll be together forever!"
Teen 1 response: "I feel so lucky to have found him at such a young age! <3 [boy's initials]
Teen 3 response: "I'm so happy for you!"
Another month or so later:
Teen 1: Song lyrics to the effect of, "My broken heart will never beat again. I'll never be happy again. The skies will always be BLACK. </3"
Teen 2 response: "You're too good for him. He doesn't deserve you!"
Teen 3 response: "Let's kick his ass!"
Rinse and repeat.
My point? When teens are in the moment, everything is very much exaggerated. All the emotions run through them at a much faster and more fierce level than they do an adult. So when you're writing romance scenes for teenagers, you have to keep that in mind. Remember that they live fully in the moment, without much thought to what could happen tomorrow. (I'll put a disclaimer here that nothing is true for everyone, this is just an observance I've made on teens via Facebook.)
Have any of you seen exchanges like this go down via social networking? It makes me chuckle and shake my head, but then it also sends me running back to my WIP to dig a little deeper into that endless depth of emotion teen girls seem to have.