We order our groceries online.
So we each add what we want to the order (I do the keto/zero carb stuff, he does the extras he wants, the carbage and so on).
Then when I cook I do the meat and the low carb veg, he adds in any extra carbs he wants.
Seems to work quite well, although every carb he adds is either processed and doesn’t need cooking (bread, etc.) or microwaveable.
He knows how to do keto, and does it to control his weight, in bursts, so he ‘gets it’ and realises that I need it.
When I recently went zero carb, I kind of lost interest in doing his veg, and felt quite bad about it, but we settled on a new form of compromise, which works well.
He managed not to starve before he met me, so it isn’t like I have responsibility for feeding him every mouthful.