From S&S "JMHO...but maybe Mrs. Puppy is having a hard time allowing herself to be someone else with you. She has locked herself into one role and is having a hard time letting it go. She wants to, but maybe shes afraid of what letting you see "that" side of her will do to your relationship. Not realizing that letting you in will only deepen the relationship. Exploring your sexuality with someone also lays your innermost feelings, desires, etc...bare to someone else and I think she fears that most of all."
This is what I'm trying to say, in a much more concise and tactful manner. :-)