The diet of a spouse can be an influence.
My and my wife's diets are similar. No, they are not exactly the same but difference can be a bother and, because of that, are limited if not eliminated.
Over years, I tried quitting tobacco many times. One time was when I first met the lady who became DW. She was strongly opposed to smoking. I had it so very much associated with work, entertainment and the outdoors, her attitude was something I just worked around. Nah. I wanted to be an ex-smoker and her emotional response to my relapses were a good motivation.
Steve