I guess she doesn't eat mayo, or she doesn't know how it's made. I assume you don't go out of your way to make sure she knows stuff like that.It has nothing to do with the fact that egg cooks or not. The sheer knowledge that egg goes in raw and she will not touch it, for that matter she actually doesn't touch anything with egg, I mean like food, desserts are ok, cooked desserts, not mouss. Well, cheese omelet is the only thing I know she eats that is egg.
There are lots of mousses that are not made with egg.