A Secret Shared with My Partner

Hi everyone, I'm a trans woman in my early 30s and have been in a happy relationship for over three years now. We love each other deeply, and we're both open to exploring all kinds of things together. Lately, though, there's something niggling at me that feels... off. It started when I discovered an old fantasy about being tied up and dominated by someone who isn't gentle, rough play, if you will. The idea is exciting, but it scares the hell out of me too because my partner is so caring and careful in everything we do sexually. I know he would never push or force anything on me, and I trust him completely. But this side of myself feels like a dark secret, especially since it's so different from how affectionate our usual sex life is. How do I talk to my partner about this without scaring him off? Am I being silly for feeling this way, or is there something here that needs to come out and be explored together?