I didn't see a lot of overt control, which I think was good, as that is one thing that concerns me. A lot of the time, Cindy seemed indulgent in a way that was uncomfortable to be around, if that makes sense. I have certainly had partners where I will joking say things like "isn't he the cutest thing?" and stuff like that, but it seemed like a very uncomfortable level of sugar-mama-ness.

There was also a lot of awkwardness at some point, as Cindy wanted to go out on a more challenging hike with another friend, and made a sort of big deal about leaving Carl behind for that hike and appeared to get bent out of shape when Carl organized doing something with someone else and didn't seem to be put out that they would be doing separate things for that day. I tried to stay as minimally involved as possible, but it appeared that Cindy was mad that Carl was happy to do his own thing and be without her. I don't know if that would be a sign of control, and again, I don't know how much of this would seem normal to me without the age gap, because it bothers me so much.

I'd like to believe that without the age gap, if my friend was bent out of shape that their new squeeze wasn't bothered that they're not spending the day together, I'd ask them what their problem was and remind them that the new relationship has had a whole life without them and that time apart is normal and healthy. So I think that would apply here too.

The person who brought up the age gap actually had a teen pregnancy and flat out said to Cindy that she felt uncomfortable with the relationship because Cindy and her are nearly the same age and Carl was only slightly older than her son. I am much closer with the person who said that (and know her son quite well) and so that statement really hit me hard and got my squick levels up.

I'm honestly not sure if my friend has dated younger people before. I usually don't ask ages (I think most of my friends don't), and as long as I've known them, they've only dated one other person who is a similar age to them that I've met. I think most of the others have been more of the FWB sort.

I think the biggest other red flag was that this was a week trip and originally, their other partner was going to come. Other partner changed their mind and didn't feel physically up to all the hiking and hardcore exercise (recently recovering from being quite sick) so when Cindy said "I could invite my new dating partner", we all said "cool".

We get there, we get along our way and we find out 1) the age gap and 2) when Cindy ask about Carl joining, they had been dating about a week and a half. By the time we went camping, they'd been dating 2 1/2 weeks. This was a rough enough trip (no access to civilization for nearly 2 weeks) that the idea of Cindy inviting someone she'd known for that little time was really shocking. It was one of those "we met and by the end of the night, we were together" kind of starts and while I do think that yes, that is hella romantic and sometimes it works out, throwing that person into a larger friend group with that little of an amount of experience with them was NOT a good idea.

That alone has spurred a larger conversation among the group about asking more questions about new joiners. The rest of us assumed that anybody invited along would be enough of a known quantity that the person inviting them would be able to vouch for them being a good camp mate and such.

Carl was not a bad camp mate, exactly, but did make several rookie mistakes in the beginning, one of which resulted in an injury that didn't need to happen. And with the monopolization of conversation, the nighttime hangouts were a lot less fun and comfortable. Also, to be clear, this was a group of slightly more than a dozen people, and about 1/3 of them are trans or nb.

edited to add: I don't have anything personally against Carl, but I really don't want to get to know him. The trauma dumping was also a real problem, and several times it poked up against my own traumas. Our camping trips are usually light-hearted affairs where we can relax and be ourselves and not worry about some of the sort of day-to-day things that can happen and brush up against a trauma. Someone did try to gently address the trauma dumping with Carl, and he didn't quite seem to get it. I definitely do not have the mental capacity right now to talk to Carl about it myself, and I think that I am more upset than I normally would be because it feels a bit like Cindy dropped a bomb on us and what was supposed to be a relaxing, renewing trip turned very stressful and frequently flat-out unenjoyable.

FTR, I don't think that I would try to actually talk Cindy out of the relationship. Like you, I already know that doesn't work.

I think it's more that I felt like I needed validation that the "because we're both trans the power imbalance isn't a problem" statement really was bullshit, and it's OK to call it bullshit, because it didn't feel like it was "mine" to call bullshit, as a cis person.

And additionally, because of the whole "because we're both trans, the power imbalance isn't a problem" statement made me feel guilty for being so judgemental, like I am doing something wrong. Like thinking differently of Cindy for having this relationship is wrong.

And to address the part about her making sure he is building his own life and such, that was also brought up by the friends who tried to have a convo with her, and she shut it all down with a lot of annoyance, from what I heard. The general gist was that the people bringing up those things were being ridiculous, he's an adult and she should be able to trust him to do all of that properly, she doesn't need to do anything other than enjoy this relationship.

I think what I'm getting out of the responses is that it's OK for me to feel the way I feel, but it's not necessarily my thing to bring up. Unfortunately I have a lot of heavy stuff going on with my life right now and I don't have the bandwidth to really handle these additional feelings about Cindy & Carl in the way that it should probably be handled. But I do feel like less of an asshole for my gut reaction.