If neither of you want anyone else to know, why is the secrecy part of it an issue?
My wife has a fantasy about being with much older men and she doesn't want anyone else to know about it because she's a little embarassed and she thinks it's a personal thing between us. I never once felt like I was "forced" to keep a secret from my family and friends or felt disloyal to them b/c of it. I'm a little confused as to why you do.
As far as her having feelings about my CDing, I get that - sometimes I think it's pretty weird myself. She may not enjoy it or want to partake in it or even wnat to know when I'm doing it, but I have to say that whatever shame she has around it is really her issue...and I'm struggling not to make that my shame too.
If I pranced around the neighborhood or told friends, neighbors or family, or if I insisted she do it with me, then yes, her life would be concretely impacted and that would be forcing all of societies stigmas and ridicule on to her. But as it stands now...what I'm doing isn't wrong. She can feel whatever she wants and I've talked to her and listened, many times. But as I've said on this forum before, she knew about it a month into our dating. If it's an issue for her 13 years later, I really can't carry that around with me.