Casdon
Surely no coeliac would neglect to tell their host of their condition? It’s a lifelong condition, and the repercussions for the sufferer of eating food with gluten in are debilitating, often for days afterwards. I’m very surprised that they didn’t tell you when they received the invite Newatthis, or at least check with you that the food was safe to eat before he put fork to mouth. Its water under the bridge now though, there’s nothing you can do unfortunately.
Surely no coeliac would neglect to tell their host of their condition
No they certainly wouldn't.
It's an autoimmune condition, not an allergy but eating even a tiny amount of gluten can cause real problems.
I'm sorry Newatthis that you feel guilty about this but it wasn't your fault and you did check beforehand.
As you've been invited to their house for a meal since then, they obviously realise you didn't know and don't blame you.