SpaceArcader said:
Where I'm from, sound means good. The thing that gets me is that she seemed a nice, intelligent albeit quite mad but she was a girl that was stuck into her books and music. Not to insult people here, but she appears more common now than the time I had met her previously.
Now that's a common story. Good girl goes bad. Although not really bad. I think part of it is that's there's more pressure on girls to fit in and conform than boys. Boys are celebrated for their individuality. You think about your group of friends and you probably all play a slightly different role in the group. Girls do as well but there's more focus on popularity and fitting in (these are very generalised, broad statements though).
But we've all been there. What's the reward for doing the right thing? More study, more anxiety, fewer friends, or so it seems. We all go through phases where we'd rather opt out and just make life easier for ourselves. I think that's fine, we all have to do it, and it's important to explore your life like that. But the danger is how far down she wants to go. If she ends up smoking everyday then she's pretty stuffed. If it's once a week then she's still making a distinction between being on duty and off duty as it were.
To put it all another way, we all have our vices but most of us know when and where it's safe to indulge them. For some people they get carried away and the vice ends up defining them; alcoholic, gambler, stoner, junkie, whore, angry dude. Lots of research shows intervention helps but more research has shown that it's got a lot more to do with the person than the people around them. If she's going to become a stoner, then she's going to become a stoner. If she's not going to be one, then she won't. You might have some impact on that but chances are it's a row boat versus a steam paddle. So don't beat yourself up about it. It's not your job to "save" people and trying to get involved will probably back fire on you.
Good luck.