Marriage Kink Experiment Gone Wrong?

So here's my situation. I've been married for about twenty years now to a lovely woman named Rachel. We've always had an open relationship, and I think she enjoys the occasional fling too. Recently, we decided to spice things up by trying out this kink idea where one of us would pretend to be someone else during sex. It's not about cheating or anything like that; it’s just role-playing within our marriage. Anyway, last week, Rachel suggested I play the part of a much younger guy she supposedly used to date when she was in her late twenties. She mentioned some specific details and how this imaginary ex-boyfriend was more adventurous back then. Now, I'm forty-five, so playing pretend isn't exactly what I would call my strong suit, but we agreed it could be fun. When the night came around, Rachel set everything up just like she imagined, flowers everywhere, candles, dim lights... It felt almost surreal being this younger guy persona. We went through with it, and honestly, it was quite intense at first because I really tried to get into character. By the end of it though, I couldn't help but feel a bit awkward. Afterwards, Rachel said she loved every second of it and that it reignited something in her. But me? Well, I'm just not sure if this is something worth pursuing further. Does being too close to your partner's age gap fantasies make it less appealing when you're both over forty? Am I the asshole for finding the whole thing a bit off-putting?