My Partner's Other Half

I've been in an open relationship for a few months now. My partner, Jane, and I agreed that we would pursue our own interests, but still maintain the emotional connection and support system that we share. She has found someone she feels very close to emotionally and physically, let’s call him Alex. While I'm happy for them, there's this gnawing feeling of insecurity deep down inside. Jane and I have always been incredibly compatible when it comes to our sex lives; we push each other’s boundaries in a way that is exciting and exhilarating. However, recently she has mentioned that with Alex they are exploring different dynamics and scenarios that are quite... well, let's say unique. BDSM elements come into play that aren't part of my repertoire. Last weekend, Jane came back from meeting up with Alex looking flushed and excited, which isn’t uncommon. But there was something different in her eyes, an intensity I hadn't seen before. She told me about a CNC scene they had done, consensual non-consent roleplay, where Alex pretended to be a dominant figure who forced her into various scenarios against her will. Hearing this made my heart race for reasons I can't fully explain. Part of me feels thrilled by the thought that she is pushing these boundaries with someone else and exploring new heights in her sex life. Yet another part wonders if there's more going on between them than just roleplay and experimentation. They both seem to have an unspoken understanding, a chemistry that's palpable even from afar. In all honesty, I found myself curious about it too. Would it feel wrong for me to want to try something like that with someone else? Or is my concern misplaced, and should I be focusing on our own adventures instead of worrying about theirs? As the days pass, this curiosity continues to grow. I'm not sure how to approach Jane about my feelings or whether it’s healthy to explore similar dynamics myself. Right now, all I know is that something has shifted in our relationship, and while I’m still committed to making things work, there are new challenges ahead.