Would you break up with someone if you wouldn't date a smoker and they ONLY started smoking after you started dating?

Let's say you wouldn't date a smoker (cigarette or weed). When you met your SO, they didn't smoke at all. Now after some time in the relationship, maybe from their friends' influence or bc they just wanna try, your SO has started smoking. Very frequently. Would you break up with them then?
Would you break up with someone if you wouldn't date a smoker and they ONLY started smoking after you started dating?
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