My Poly Partner's New Kink Caught Me Off Guard

So here’s a funny thing about me, I’m pretty open-minded when it comes to sex and kinks. My partner Alex is the same way, we have an open relationship which gives us both plenty of room to explore our sexual desires without any hard-and-fast rules. We’ve tried everything from blindfolds to roleplay, and we always make sure to communicate what feels good and what doesn’t. Recently though, Alex brought up a new kink they wanted to try out. They mentioned something about getting into submission play, which wasn’t entirely surprising since they love exploring different aspects of control in our relationship. But then Alex got super specific: they wanted me to tie them up while we had sex. I mean, okay, that sounds fun on paper. You get to be the dominant one and it adds a bit more excitement to the mix. The thing is, once we started, there was something about being able to move freely but having my partner completely restrained that threw me off guard. It wasn’t just the act of tying them up, I had been fantasizing about doing that for years, but the feeling of power and control over someone who’s willingly giving it all away. To be honest, when we first started, Alex was a bit unsure too. But as soon as I began to guide their body with mine in that moment of total surrender, they started making these little noises deep in their throat that turned out to be incredibly erotic for both of us. They were tied up and helpless, but still able to respond to my every move and touch. It was the most intense thing we’d ever done together. So here’s where I need some advice: I’ve always been on top when it comes to being dominant in our relationship, but suddenly this new dynamic is just so different that it feels almost... invasive? I know Alex enjoys having control at times too, and they’re very much into the role reversal we experienced. But there’s something about me taking charge of them like this that feels both liberating and unsettling. Am I overthinking this whole thing, or does anyone have any thoughts on how to balance these new feelings with our established dynamic? Should I let Alex take more control in turn, or is it okay for me to continue exploring the newfound pleasure of being completely in charge? It’s like suddenly discovering a side of myself that feels very raw and powerful. Let me know what you guys think!