I find that people who don't have a fetish of any sort (or don't know they do) will respond poorly or at least indifferently to being introduced to something like this forum. I have brought up kinky topics in conversation and I'm surprised how many folks strike an attitude like : "what's wrong with regular old sex!? Isn't making love enough?"
These people will never understand
But if your partner is a bit kinky themselves, even if its an unrelated fetish from facials, I bet she'll respond better than you think. She probably won't be super excited about it but don't take that as a sign of disapproval, she is probably just curious. And if she knows that you frequent a forum PRIMARILY about facials, then she'll at least know how serious your interest in them is. I used to play that part of my sexual imagination down a lot as it's akward to talk about, but if she knows about the forum then she knows you like it A LOT!
MY OPINION: Come out about ff for everyones sake (what if she wants to be gf of the month)
