Best Friend concerns...

Remember those old after-school shows where one friend would try to help out the other when they noticed his/her boyfriend was a bastard/was wasting his/her life away and then it pretty much ruined their friendship. Yeah, that actually happens.

So you can do one of two things: let nature take its course and chances are she'll realise it on her own, or sit her down and discuss it in a mature fashion letting her talk the most while you guide with questions. Depending on the person you have to be careful where you interject your opinion, so it's best not to even bother until the conversation is pretty much wrapped up. And even then you might want to say it in a delicate, but straight-forward manner.

Or just say fuck it and tell her how you really feel without considering anything further. Who knows, might work.

Jam it back in, in the dark.