Why doesn't my boyfriend like my Nazi ?

My Nazi makes my boyfriend uncomfortable. I NEED ADVICE. My boyfriend told me that he finds my Irma Grese/Ilse Koch-style Third Reich dominatrix costumes to be disturbing; he seems reluctant to participate in Lebensborn role playing and even Auschwitz guard/ male prisoner role playing. He also suggested gently that I take down the Hitler Youth propaganda posters that are currently hanging over my bed. Is Nazism a 'turnoff'? If so, why?