So Open-Ended It's Closed Off

Alright, so I'm in my mid-thirties now, living as a trans woman, and I’ve been in this open relationship with Alex for over two years. Alex is also a bit older than me and has had a very non-traditional approach to relationships since way before we met. From the get-go, it was clear that our dynamic would be about mutual respect and personal growth within a flexible framework of rules and boundaries. Recently, though... things have felt kind of odd. You know how it goes, Alex has been bringing home guests more frequently, which is totally fine and agreed upon by both of us. But here’s the thing: I’ve started to notice a pattern where these guests are women who are in their twenties or early thirties, much younger than Alex or me. At first, I just brushed it off as coincidence... but now, every time he introduces someone new, there's this subtle hint of a glow about them that gives me pause. I've tried to talk to him about my feelings... but the conversations never really lead anywhere meaningful. He insists everything is cool and keeps saying how important he thinks open relationships are for personal freedom and exploration. I get it, I do, but sometimes, hearing these younger women referred to as 'excellent partners' or 'very adventurous' makes me feel a bit outdated. It’s not like I want Alex to stop being with whomever he wants; the whole point of our relationship is mutual respect for individual choices and paths. But there's this part of me that feels... less seen, maybe? Or just more aware than before of my age, which isn’t something I typically dwell on. Is it really normal to feel this way in an open setup where everyone’s consenting adults with the same rules? Am I being unreasonable by expecting him to consider how these choices might impact me emotionally? Is there even a standard answer for that...