If someone smoked for a year or two and then quit I wouldn’t worry so much about the long term health repercussions (though I’m sure they are real). What I would worry about is the possibility that they will smoke again.
If you marry someone who has never smoked, what is the chance they will start smoking later, after getting married? Very unlikely, probably 1% or less.
If you marry someone who used to smoke but quit years ago, what is the likelihood they will start smoking again later after getting married (perhaps when they start getting stressed out with their job or growing family)? Much, much more than 1% — a significant chance.
If you marry someone who used to smoke but quit relatively recently, what is the likelihood that they will relapse and start smoking again? Very high!