Mine just wrinkles her nose and says that I "smell like gum" and am I "going out to fake-smoke [my] fake cigarette now?" (I go outside to vape when she is home, even though the landlord allows it inside the unit and I do it all the time when she's not here, because apparently "gum" is an offensive smell to her -- when she's not chewing it to cover up her cigarette-breath, anyway.) When I first started, apparently I was "too" excited about it because she asked "if there was {slang term for any highly-addictive substance or activity} in there" and if she was "going to have to take it away from me." So I don't talk to her about it anymore, I just keep my mouth shut and go outside for "smoke breaks" like I used to do.
She is not a heavy smoker (nor was I, before I switched, and she smokes even less than I did), but she is still very much a smoker, and firmly not on board the vaping train. All the flavors "taste like gum" to her, even the unflavored (very slightly sweet from the VG content) DIY I mixed up for her to try. I mean, I guess deep down, on some level, she probably appreciates that I'm saving $80 bucks a month and far less likely to die a horribly painful death from devastating lung disease, but outwardly, all I get are the wrinkled nose, and condescending remarks about gum-smell and the legitimacy of my "smoking" implement.