Definitely something you think your partner would have mentioned…

Everyone sucks here. If you have an allergy, you NEED to tell people who are cooking for you. Likewise, if you're cooking for someone you've not cooked for before, you NEED to ask them if they have allergies. Both parties should have brought up the topic themselves, willingly. Not to mention how fuckin rude it was of OP's partner to not even mention it. Hell, if even one side of this had followed this rule, it wouldn't have happened. Sucks that people are accusing OP of doing it on purpose though.

I don't think it was your fault. You gave them every chance to say something and they ate it off the plate when it was presented to them.

Dump her! For genetic reasons. Your offspring will likely be constrained to eating plain mush and you'll never get to eat anything tasty again!