Sure, you can write thoughts in third person for a third person teen/tween narrative. It would look like this: “He leaned in but she turned away. No way would she kiss him. She’d rather eat a worm.” But you can also pop out of third person to first, if you’re so inclined, using italics to signal the shift to kids: “He leaned in but she turned away. In your dreams. I’d rather eat a worm than kiss that snout.” Some find that a more dynamic mix. It depends on you and on your story. Gotta love choice.