Was I Wrong For My Trans Desires?

Hi there everyone, I'm going to lay out a situation that's really weighing on me. I've been in a relationship with my girlfriend, Sarah (not her real name), for almost three years now. We have a great dynamic and she means the world to me. I’m 35 and transitioning as a trans woman, but this isn’t about that part of my life. It’s more personal than that. About six months into our relationship, Sarah mentioned something that took me by surprise. She talked about her fantasy involving another man with long hair and feminine features - it wasn't about gender identity, but I couldn't help feeling a little connected to the idea. This was just a passing comment at the time and we didn’t delve too deep. But last week, things escalated. We had a dinner date and Sarah brought up that fantasy again, this time more seriously. She asked me if I would ever dress like the character she described for her. To say it stunned me is an understatement. The way she looked at me, though, was intense and full of desire. We agreed to talk about it more later - but after dinner, my mind was racing. The thought of playing a role that matches my own journey in transitioning felt oddly familiar yet unsettling. I love Sarah deeply, but the idea of dressing for her as an embodiment of her fantasy...it's something new and challenging. Now here’s where I'm at: what if she thinks this is about me wanting to be someone else? Or worse, does she think my identity isn't real because it matches a fantasy character in her head? This week has been full of self-doubt. My thoughts keep circling back to whether I should even entertain the idea or just let go and focus on who we are together without this roleplay. I honestly don't know what to do. Am I being unreasonable here, overthinking things because they hit a sensitive nerve? Or is it right for me to explore my boundaries more in the context of our relationship? I'm so conflicted, and I really need some perspectives from you all who might understand this from different angles. I guess at its core, I’m wondering if playing into Sarah’s fantasy would be affirming or detrimental to my sense of self. It's such a delicate balance and I’m feeling lost right now. So tell me, what do you think? Am I being unfair to myself here, or is it okay to explore these new facets of our relationship in a healthy way?