Conflicted Kink Fails Me Again

I've always been a fan of experimenting with different kinks to spice up my life. I recently started dating someone who was open-minded about exploring these things together. We had a lot of fun trying out various role-play scenarios, and the chemistry between us just kept getting hotter with each session. However, there's one thing that's been bothering me for some time now. I love engaging in more submissive kinks during our sessions, but something always seems to go wrong when it comes down to actually going through with them. Maybe it's a fear of commitment or just plain hesitation, but every time we're about to start, I back out at the last second. Last weekend, we planned on diving into more intense play that would have pushed me beyond my comfort zone. We spent hours discussing and preparing for this moment. As the night drew closer, I started feeling anxious and unsure of myself. I kept telling myself it was because I wasn't ready to fully commit yet, but deep down, I knew that wasn't entirely true. We were in bed together, both excited and nervous as we got undressed. Once we were naked, the atmosphere between us became electric with anticipation. She started gently tying me up with silk ribbons, ensuring they wouldn’t hurt my skin. As she positioned herself over me, I felt a strange mix of excitement and fear. Just as she was about to take things further by whispering commands that would have left me shivering in desire, I suddenly broke the moment. It wasn't because I wanted to stop; it was purely out of anxiety about going all-in on something I've never fully done before. She looked at me with a mix of disappointment and concern. We didn’t speak much afterward. The next day, we both avoided talking about what happened, pretending that everything was fine when we knew deep down that the unspoken tension between us had grown. How can I move past this constant fear of diving deeper into kink with someone who cares deeply for me? Is there a way to overcome these mental barriers and finally experience something new without sabotaging my relationship in the process?