For one, don't apologize for the way her feet look. They're very pretty, and the important thing is that you're happy with HER as a person. I feel that as long as you show that you care about her, she should accept your fetish. if she doesn't then she just probably isn't the right person for you. You can't change who you are, and as long as you're not harming anybody, why would you want to? I would just tell her casually. Don't act embarrassed by it. Have confidence! The first time I told someone I had a foot fetish was this girl I met online, and I wsn't even dating her. I was surprised, however, by how easy it was to just let go and say it. it was very liberating. Maybe get a little drunk and tell her! Good luck man