Girlfriend smoking?

This is coming from an ex-smoker (female) who has stopped smoking with the help of her boyfriend - I think you are well within your right to give her the ultimatum. Just like you can't force her to stop smoking - she can't force you to be okay with it, and to be honest, if she won't quit for you, it speaks volumes about how little she cares about you, in my opinion. I know how hard it is to quit, but losing my partner because he can't live with a smoker would have been ten times harder. Think of it this way, tobacco and nicotine are drugs, just like marajuana, and nobody would expect you to stay with a pothead. The only difference is the legality - it's still destroying her, and in my opinion tobacco is worse for you. Talk to her about it and tell her you can't ultimately stay with a smoker the rest of your life - but be sure to point out that if she chooses you over her drug that you will be patient and support her while she fights the addiction. Good luck! X