No need to get in a stew about the stew! Sorry - couldn't resist the pun.
Ah, but t's never about the _____ (fill in the blank - in this case, "stew"), is it?
I don't know if this may help or not, but men and women think differently about things. Does your hubby cook all the time? If not, he may have been especially proud of his creation and offering it to you was done as a loving act. He may have interpreted your rejection of the stew as a rejection of his love or even him.
If he's generally there for you most of the time, my suggestion would be to fawn all over him for making such a delicious stew and have a cup. Eat slowly nd feign fullness or tell him it's so good you want to make it last for a couple meals. One cup won't derail your efforts, I promise.
I applaud you for wanting to track everything, but perhaps think of it this way: you are on this healthful journey for life. And you have married your husband for life. Sometimes, life has moments where we can't practically control every detail (count every calorie, etc) and part of this whole journey is learning to navigate this very thing. Fifteen months since I began my journey and I'm still practicing this part!
So view the occasional not-tracking (or estimating) as practice for all the future times. That might take some of the anxiety out of it.
In the end, you want to learn how to manage the eating part as a normal, natural part of your healthful journey and you want a happy spouse, too.
Good luck to you both!