Here's a useful tip-- if your Significant Other won't be eating a meal with you before kissing is likely, keep a toothbrush and travel toothpaste handy for him/her to use.
DD's boyfriend is super- gracious about this. No questions, no balking-- and it's not like he's eating her allergen, just things that are very likely contaminated (shakes at some restaurants, stuff fried in pn oil, etc.). With her sensitivity, though, she's wary-- and rightfully so.