I'd stand by my point that women are more ashamed of sex in general (straight or not).
I'd suggest a therapist for this type of outlook. It's a lot more simple than you think. Since most girls grow up having been called a slut and other negative names by boys trying to score cheap points and keep the upstart girls in their place, girls just prefer to keep private matters private.
Don't make it any more complex than it is. Can you say, "It's none of your business ?"
Who's being sensitive now?