I also think for a lot of us a factor in what makes us fat was spending too much time thinking, doting, caring for other people and not ourselves.
It is a shocking situation when your fat partner takes a turn and suddenly spends genuinine time on themselves. I can understand how that may create a perception of an obsession or that they have gone nuts with this new diet and don't spend enough time with loved ones.
I have observed though, that some of my healthier friends spend a considerable amount of time exercising (jogging, yoga, gym etc) without their spouses. I have yet to hear one of their spouses complain. I think it is because they came into the relationships with a different balance and a different set of expectations. It was always clear to their partners that their health and body was a priority.
I think over time it becomes clear that it is not an obsession, rather a normal part of self care. And I don't think spending a certain amount of every day on 3fc is weird

You sound pretty in control to me, CakeBatter.