It is not necessary to advise, but to help get rid of the bad habit. All smokers want to quit, but not everyone can do it alone. They need help and support because this is a difficult job. Anyone can give advice, no need to strain right there.
I don't think it's right to "forbid" anything to anyone at all. Each person is a separate person with their own habits and views, you can only advise, ask and recommend, but not "forbid". This will only lead to the worst result, believe me.
I can cite a story from my life: at the time of meeting my future husband, I smoked for several years, and, moreover, I liked smoking. That is, I absolutely did not want to quit. My husband, who, accordingly, did not smoke and could not stand the smell, at first politely asked me to do this in strictly designated places. Then he gave facts about smoking a couple of times. All this was very tactful and without "orders". I very soon realized that he didn’t like my habit and quit because he was dearer to me. Of course, for several months after that, I periodically smoked with my friends at the university, but I didn't buy packs anymore and I didn't smell like cigarettes. Now I don't smoke at all.
I mean, be more patient and gentle. You have no moral right to order, just show your half that her habit is unpleasant to you. If two years ago my husband would have started talking to me in an orderly tone, this would have caused only negativity in me, and we might not have gotten married. So everything depends only on you. Good luck!