It is so hard to pin down what causes a flare! I have had flares sometimes when not even being super-adventurous with food. Sometimes they are just destined to happen anyway, and I have no idea why.
I know though, that I have not been able to tolerate mushrooms since January 2020! I love them too, but too bad. I daren't risk it.
Maybe there was also another ingredient in the (I'm sure really tasty) slow cooked meat your wife made?
...Some herb? Garlic? Onion?
I am, strangely, okay with chocolate. But not everyone is. It can also depend on the chocolate. Not all choc. has the same ingredients. Mine is pretty all-natural, but is a milk chocolate, so contains lactose etc. But for some reason it never upsets me. Thank goodness!! But some contain awful trans-fats, additives, sorbitol etc.
Hoping it doesn't take too long to come out of your flare. Take care.