It's funny, both my wives (one at a time) smoked when I met them (even though I was a non-smoker) and both gave up just_like_that when we knew we were becoming an item.
My Dad smoked the odd cigar (that made me feel sick, especially in the car) but most of my family and friends are non-smokers so that helped.
And I think it is 'lucky' ('A Good Thing') especially these days with as many pressures being put on smokers both where they can smoke and the cost (they know the health risks). It was a cool thing to do when I was a lad (some of my mates did) but luckily being 'in' or 'cool' have never been priorities to me.
I have always tried to be very supportive of anyone trying to give up ... supplying them with mints or whatever they found suitable as a distraction. Sometimes it worked but I think it's one of those things where you really have to *want* to stop yourself.
Cheers, T i m