I think bringing something is an excellent idea, if they get butthurt, they can deal with it,
I have issues with some forms of fat, it was just slightly before the whole colorectal cancer thing, we had thought it was originally a gallbladder issue [fat digestion/processing issues are a common differential for gallbladder issues] but post treatment, I still have issues with fat content and fat type is also important. Canola oil is always problematic for me, and I tolerate animal fat better than veggie fat though ultra neutral rice bran oil works best for me.
I have learned the immodium thing [though for the upcoming flight/layover/flight thing to Nevada 5th - 12th I am simply not eating solid food for 12 hours before, taking the ‘deathpoo’ combo of 2 immodium/1 lomotil washed down with a dose of kaopectate that I was doing during chemo/radiation to effectively shut down my digestive tract totally til I get to the hotel. Will be repeating it for the trip back.
Sucky for your wife, but unless you have digestive issues, you don’t realize how horrible it can be.