I Admit My Secret Kink

I met her when I was 21 and we've been together for five years now. She's amazing, but she doesn't share my particular kink, something about restraints turns me on like nothing else. We tried it once at the start of our relationship and it went great, but since then, every time I bring it up, she changes the subject or suggests we try something new instead. It's not a dealbreaker for me, just something that makes me feel alone sometimes when we're exploring other things together. She's supportive of my interests in general, but this one has always been her limit. Last weekend, when I was out with friends, I ended up at a party where there were bondage toys and demonstrations going on. The sight of two people experimenting got to me more than it should have, I found myself sneaking glances the whole time, fantasizing about being part of that too. I know it's not fair to her, but it's been nagging at me ever since, wondering what would happen if I could finally let go and act on it without her there.