Sex in and of itself is neither moral nor immoral, it is just what it is. In my opinion all of the attempts to control women and the expression of their sexuality stem from fear. Fear on the part of men that somehow they won't or can't measure up sexually so if she doesn't have a wider knowledge of what it's like the men won't experience feelings of inadequacy and fear on the part of other women who want to control and limit the competition. And this aspect of women policing other women's sexual behavior can also be rooted in fear of inadequacy as well as competition for mates. The fear in men is deeply visceral and seems to me at least to be rooted in the fact that the female sexual response, i.e. multiple orgasms is an evolutionary development to give her an incentive to copulate with several males as opportunity arises. All the rest of the guilt and angst is just icing on this not particularly appetizing cake.