flighty

1. ADJ If you say that someone is flighty, you disapprove of them because they are not very serious or reliable and keep changing from one activity, idea, or partner to another. 反反复复的[表不满]

Isabelle was a frivolous little fool, vain and flighty. 伊莎贝尔曾是一个轻率的小傻瓜，自负而轻浮。