What is the best way to get my girlfriend to quit smoking?

My girlfriend has been smoking for a few years before I came into her life and now since we are at 6 months I told her that I want her to start quitting because I hate smoking.

She has cut down to almost 3 a week when shes around me, but when she is with her friends (current smokers) or is drinking then she chain smokes non-stop.

It’s obvious that her trying to quit isn’t really cutting it and I want to find a way for her to be able to quit throughout the whole day everyday.

Any suggestions would be appreciated.

Keep in mind any attempt of me to take action by force results in her getting quite pissed at me, which stresses her more and makes her smoke more, so I’m trying to find an easier way for both of us

Thank you
*EDIT*

Umm we do get drunk more often then usual and the 3 cigs a week is ONLY around me, but she smokes at least half a pack if she’s with her friends.

It’s not a case that she’s has dangerous habits now, but I want to prevent them later if this goes any further. Lord knows if I even thought of asking her to be my wife or somethin’, then smoking would be something of the past