Hello.. Well sometimes looking at the peers of her age..they get that inferiority complex that gets in their mind and which makes them indulge in many activities.. It's better to sit and talk to her in personal..make her understand and listen to her patiently too...its common for her age...but definitely need to talk about it...you can as well take the help of counselllor too

Behavioural change might be due to various reasons. It might be adolescent adjustment reaction or personality issues. May be she is getting trapped in a relationship. Or she might be developing a psychiatric disorder. Best it's too talk to a professional about it.