My BF of 1.5 years has been part of a sporting community for many years but has not actively played the sport himself since before we met, although he still hangs out with those folks and goes to events. Last night, for the first time in years, he decided to go to an open session at the sporting facility and play the sport. He got back somewhat late so I was half-asleep and just asked him if he had fun and he said he did, and he hopped in the shower and that was about the end of the conversation.
This morning, he told me that his most recent ex happened to have shown up at the open session too. I said, really? Wow. I didn't know she ever went to the facility (which is somewhat of a hangout as well as an athletic facility - I've been there before). He said he knew she'd been in the past but didn't think she'd gone recently. The sport is something that is a one-on-one type of deal, so I said, "You didn't play with her, did you?" ... phrased that way because I really didn't think he would have done so. Well, yeah, he did. I said, "Was that weird? and he said it wasn't.
I'm realizing that since this is still on my mind a few hours later, even if it wasn't weird for him, it's weird for me. I don't feel comfortable with him playing this sport with his ex. But I can't articulate any concrete reason for that - our rela'ship is good, and my understanding is that she is in a rela'ship also, so I'm not worried about cheating or temptation. It just feels really intimate to be playing a one-on-one type sport with someone that you used to be in a relationship with. They're not friends, so him spending time with her in any capacity hasn't come up before. I'm more of an individual sport person, so when I've tried to come up with an analogous situation for myself, it doesn't really work - if I were running a race and an ex happened to be running the same race, I'd say hello if I saw them and that would be it (the way I run, they'd most likely finish 20 minutes before I did).
My question, then, is, is it rude or unreasonable to say that I am uncomfortable with him doing this in the future, if I cannot provide a precise reason why? I am a pretty direct communicator, so my impulse is to say pretty much that: I can't quite explain why this makes me uncomfortable, but it does. My hope would be that we could then have a conversation about it - right now, I'd like the result of that conversation to be that he agrees not to participate in one-on-ones with her, but I'm open to the possibility that talking it through might make me feel less weird and not care.
Any thoughts? Thanks for your help!