Kinks and fantasies

Recently found out my boyfriend has a “dominatrix” fantasy which left me feeling insecure as this is something I’ve never dealt with and don’t know how to go about it. He says he doesn’t expect me to fulfill that and he doesn’t want anything else but me, but as a woman of course I’m going to feel like i have to but I also don’t know if I would feel comfortable with it not because I don’t like the concept but because he was going behind my back looking at/buying content on this. Any advice? 😄