How can I get my girlfriend to quit smoking?

She started smoking 2 months ago but then she only had one every few days but know she is on 5 a day which isn't to much I know people who smoke more but I want her to quit before it becomes fully addicted to them. When she is around me she does not smoke because she knows I do not like it which makes no sense as this shows she can control the nicotine addiction as when she came over mine she went at least 3 days without smoking. She did tell me it is stress related but when she started she was stressed out to do with her father so she smoked when she was at home but the way I see itt you should only smoke as your getting stressed so why is she getting so stressed in college?

Even if you have expressed that you don't like when your girlfriend smokes, she is able to make her own decisions, and smoking cigarettes is one of them. I can understand why you would want her to stop before she becomes a habitual smoker, but the only thing that will make someone quit smoking is when they actually WANT to quit and are SELF-motivated to quit. This has been my observation, at least.

I am a smoker, and I have quit a few times - it didn't last for long on each occassion, but when I am ready to quit entirely, I will. People telling me I shouldn't smoke does not compel me to stop. When a smoker quits, it's because he or she has made the conscious decision to do so, and outside influence may play a part in this decision forming, but outside influence alone will likely not be enough.

If you're polite, you can't do that. It's her own choice to smoke.

Otherwise, you could say, 'If you don't stop smoking, I will not kiss you anymore'. Well this one would be very rude. So I would say, be polite, and let her smoke. Either, she would smoke in secret anyway when she feels the urge to smoke.