Emotions aren't cut and dried. In fact, they're often irrational and complex. Showing the messiness of emotion is difficult, but when it's done well, it can drag the reader right into the story and have them emoting right along with the characters. Teenagers have particularly messy emotions and that's one of the reasons I love writing and reading YA so much. With all those confusing hormones rushing around, and new feelings to engage with, is it any wonder teens are unpredictable?
And unpredictability adds tension. We sit on a knife edge, unsure what the character might do. Last time they faced (add plot point here) they didn't react to it, they turned away and ignored it. What will they do this time? The trick is to show it. You don't want to say 'Jenny was humiliated'; you want to show that humiliation. Maybe her ears burn, her face flames or she just turns away to stare at the ground. Or maybe she doesn't do any of that. Maybe she doesn't let it get to her because that would show weakness. Maybe she just throws her shoulders back and eyeballs the person who's embarrassed her.
I consider myself a very emotional writer. All my books take my characters on an emotional journey. The biggest changes that occur are within themselves as a result of whatever I've put them through. I've just had two readers finish my new draft of Tail Lights and both of them have accused me of making them cry.
I guess I'm doing something right then....