Discovering My Secret Pleasure as an Adult

I'm in my early 50s and have recently stumbled upon something that's been a bit of a shock to me. I've always thought of myself as a fairly conventional person when it comes to relationships and intimacy, but lately, I've discovered this kink within me that has completely thrown me off balance. It all started about three months ago after watching some videos online, nothing illegal or extreme, just different scenarios that I hadn't really considered before. One thing led to another, and suddenly, here I am with a new desire that I didn't even know existed. To give you some context, my partner is in her 30s and we've been together for about five years. We have a good relationship; she's caring, supportive, and kind. But when it comes to sex, things have always felt rather routine to me. There hasn't been anything particularly wrong with our physical connection, but I just didn't feel all that excited by it. That changed one day when I came across this particular video online. It was about DDLG scenarios, I'll skip the specifics since I'm not entirely sure what they're called, and watching it triggered something in me. It wasn't pornographic or explicit, but there was a certain energy to it that really resonated with me on an emotional level. I found myself fantasizing about being disciplined, even if just symbolically, and imagining scenarios where I could be more vulnerable. Since then, I've been struggling internally because I know this isn't something I ever expected to want or feel comfortable exploring. At the same time, a part of me keeps urging me to act on these new impulses, mostly in private at first, like trying out some light role-playing games when we're alone together. I'm not sure where this is going to lead, but it's been quite the journey so far. Part of me feels like I might be cheating or being disloyal by even entertaining such thoughts, while another part believes that exploring these new sides of myself could actually enhance my relationship and bring us closer together in ways we haven't experienced before. I guess what I'm really looking for here is an understanding of how common it is to suddenly discover desires you never knew existed as a grown adult. Is it normal? Am I being ridiculous or am I onto something that might just be the next step in my personal growth?