My wife went through this for a minute. Only when she knew there was gluten did it set off an insensitivity. If she didn't know there was gluten in it, she didn't react.

There are other things than gluten in wheat that can set off digestive problems.

Have your partner take a look at https://www.gloshospitals.nhs.uk/media/documents/FODMAP_diet...

Barley has gluten but in low levels compared to wheat. Its why barley bread doesn't rise that much.