Interested in feedback from anyone with a similar experience.
My W and I have been married 11 years, five years back we had
a close call and after marriage counseling have had 4 really
great years.

I get jealous because she likes to go on "girl vacations" with
her single girlfriends (in their 40's). Intellectually I don't
think whe would cheat on me, and she has told me these vacations
are just about getting time away with her girlfriends. The only
part that bothers me is she spends weeks buying sexy clothes and
shoes for these trips and always obsesses about losing weight
right before she goes. The other girls (and my wife)
are gorgeous and the
whole 4 of them together are something to see. Some of the
single girls on the trip (well, they're all single now except
my wife) hook up with guys on these vacations. They go out
dancing (and my wife dances with other men -- she claims they
are just all dancing together in proximity) and try to find
the most upscale bars where the most "interesting" people go.

That last paragraph is the "fear in me" part describing the
vacation. Again, I really do trust that my W is just having
a blast with the girls, gets a kick out of watching the others
talk to guys (she makes jokes about it to me afterwards). She
always tells me she is not into meeting men on these trips.
Neither of us have ever cheated on each other.

It still triggers the heck out of my anxiety. When I've told her
this in the past it is repellant to her. She doesn't want to
hear it. She wants me to be supportive of her chance to hang
out with these girls -- she sees it as a chance to have
close friendships with women that she never had when she
was growing up.

After her last trip I admitted my anxiety and we've had somewhat
of a marital relapse -- she hates getting into big talks
about this kind of stuff and anything that seems like
jealousy, insecurity massively turns her off.

Has anyone else had a similar thing? I know that jealousy can
be a self-fulfilling prophesy. I think its natural for me not
to like the idea of my wife dancing with other men, but since
I trust her, I need to make peace with this.

Best to all.