Keeping something from your significant other is definitely not a good thing. I was very interested in Keto and talked to my then fiance about it. She was against it, but when I talked about the science and said “hey, listen to 2ketodudes podcast and they will explain much more than I can.” She ended up listening to them, although she wasn’t a fan of their style. So she searched up other podcasts and found Leanne Vogel’s podcast and listened to it.
She was reluctant to give me her blessing, but she knew I wanted to give it a try. She agreed to let me try but wasn’t happy about it. The more she listened to Leanne Vogel, the more accepting she became. After a month of consuming the podcast and learning more, she actually debated on going keto as well. Then she made the jump to keto after she found out that it can help with Hypothyroidism and didn’t effect cholesterol in a negative way.
Give some materials like podcasts or articles about the Ketogenic diet to her, but don’t force her to listen. Tell her you are trying to take control of your health, so that you can be on the planet with her for a much longer time. And let her know that it won’t effect her normal day to day, but request that she not be negative or try to sabotage your way of eating.