My wife was not happy about me starting, but it wasn't a deal breaker, and I told her I'd keep it outside.
Then my wife didn't care for the smell of smoke on me, but it wasn't a deal breaker, and I did my best to clean up afterwards to lessen the smell.
Then my wife didn't care for the TAD and PAD, but it wasn't a deal breaker, and I made sure be open about it and keep the buying well within our means.
Then my wife didn't like me smoking upwind of window, as smoke would get in the house, and I moved to the detached garage.
When we moved to a new house that had an attached 3-season room, she was not happy with me smoking in it, so I bought a bunch of different deodorizers to neutralize the smell.
Fast forward 10 years, and at this point, she doesn't care if I smoke my pipe, doesnt care the 3 season room smells of smoke, doesn't care if I come to bed smelling of smoke, doesnt care if I buy a new pipe or more tobacco, and when camping will let me know when she likes the blend I'm smoking.
Still a long way from moving it into the house, though. I floated the dedicated room trial-balloon a few months back, and she made it very clear that was a bridge too far. I'll wait a few more years and ease the idea into conversation again and see if there is any give. Maybe by the time we are empty nesters, she'll come around. If not, no big deal, probably good to give my mouth a 2 to 3 month rest every year.
It's a give and take thing. Patience, communication, more patience, more communication, etc.
This all said, if you have the misfortune of indicating that a few bits of wood and smelly leaves are more important than her, well don't be surprised when she walks out. Don't be lured by the siren song of materialism. Don't be a gadget geek.
Lastly, depending on who in the relationship first floated the cohabitation idea, you might want to give some thought to the notion that cohabitation essentially says, "I want to be able to continue with the choice to drop this relationship on a dime, but I am too poor/cheap to pay my own rent/mortgage while we figure out if we want to enter into a sacred vow, all or nothing, relationship or not". Or something like that. You should't need to live together to know if taking the plunge makes sense. Dating is a horrible joke, but it's a necessary evil to find a long-term mate. Don't prolonged the misery with cohabitation, make a decision and move on.