Why is Henry worried about Natalie in Act 2, Scene 3? Where does he ask her to go?

In Act 2, Scene 3, Henry and Natalie meet each other at school, conversation revealing they haven't talked in weeks ("Hey #1," tentative soft rock), that Henry is worried about Natalie's drug use, and that he wants to go to a dance with her. She refuses and goes, but he chases after her.