The Unspoken Secret Between Me and My Partner

I’ve been in a long-term relationship with Sarah for nearly six years. She’s the love of my life, but lately I’ve felt something gnawing at me, a secret that’s hard to admit even to myself. We live together, share everything... or so it seems. The issue is, I find her irresistible when she takes on a certain role in bed, one where she plays a character from a fantasy novel we both enjoy, and she’s the dominant one. Sarah doesn’t know this side of me; it started before we got into the serious relationship, and I kept it hidden because I worried how she’d react. She knows I’m turned on by her in general, but this specific aspect... it’s complicated. On nights when I let my mind wander to that fantasy world, there’s a part of me that wants to scream it from the rooftops, this secret dynamic is what truly sets our intimate moments apart. But here’s where things get sticky: Sarah has never shown interest in exploring those boundaries with me; she seems content sticking to reality and romance. And honestly, I’m scared if she ever found out this fantasy aspect of my attraction towards her, it could shatter the trust we’ve built over these years. So I keep silent about it, hiding behind a mask that says I’m just fine with everything as it is. Is there something fundamentally wrong with me for wanting this dynamic in our relationship? Am I being unreasonable by holding back my true desires? Or am I justified in protecting the harmony we’ve worked hard to maintain? What do you all think?