I've told two. First one laughed at me, then when she realized I was serious, and I explained it wasn't cannibalism I was getting off to, there was some discomfort but she ended up trying to turn it into a writing exercise and tried to write some stuff for me. It was pretty hot desu, if poorly written, but you could tell she didn't really like the idea.
Second one took me very seriously, then next time we talked about it she knew a bunch of terminology, turns out she did some research. She seemed almost into it, and was way better/more enthusiastic than first girl, but after the first roleplay session she said she didn't like it and didn't want to do it anymore.
Honestly as long as you go in telling them that it's just a fetish and you are embarrassed by it, as long as your not some submissive fag during all other parts of your relationship, they will usually respect your vulnerability and either engage with the fetish or not. personally I don't worry about it costing me a relationship, because I'm smarter than to bring it up that early. oh, and I always get them to talk about their fetishes first.