At one point my wife kind of had this complex about herself. Sex was very vanilla, very infrequent. If I asked her to reciprocate at all she would say, "what, like some kind of stripper/pornstar?!"

She had gotten in her head that any sort of enjoyment of sex or active participation was indication that she was a slut, etc. Which was especially weird because she took lots of gender studies classes and was very pro-SlutWalk, pro-feminism, etc. (as am I) but the sexually liberating aspects of those classes seemed to have the opposite effect on her.

It took years of patience and talking through feelings until we started having breakthroughs, she was afraid that if I thought of her as a slut I would leave her, and I told her repressing her sexuality was hurting more than it was helping. It took her a long time to believe that, but something clicked eventually and we are all good now. Watching porn together, talking about fantasies, and playing with toys/outfits helped a lot.