WHY DOES ROXANE GET MAD AT CHRISTIAN

In Scene Five, the precieuses, Duenna, and Roxane all say their goodbyes to each other. Roxane sees Christian and tells him to sit next to her on the bench and talk to her of love. He says he loves her, and she impatiently says to elaborate. All he can say are simple phrases like he adores her, and she grows more and more angry. She says she does not like him stupid like this. Finally, against his protestations, she gets up and goes inside her house.