If you are someone who cares about a smoker, you have the classic paradox of which type of love is more helpful to them in the long run. On the one hand, you can always claim that you are allowing them to feel pleasure, which in turn is good for them in some kind of way. But on the other hand, you are also allowing them to hurt (and ultimately bring the pain of a slow, early death on) themselves with every puff. And while they could always sneak their smokes behind your back when you are not looking, at least you can make it difficult- if you really care that much.
Of course, there is always the old saying that a person can live a better life through living and letting live. Of course, as the Beatles so brilliantly put it, living and letting die is also an option which is constantly available to you. And while one could easily argue that as soon as a person is born they start to die, there is a certain discrepancy between the life span of a smoker and that of the person who lets the smoker go about it. It is not your fault if they want to take a chunk out of their own lives.
But on the other hand, the love that you feel for your favorite smoker might actually be enough to help them quit. While it is always going to be a long shot, there is always the possibility that you can help them to escape from this problem before it becomes too late for them to stop the cycle. And if nothing else, you can stop them enough to save yourself.