Maybe this reflects my lack of life experience, but I don’t think that’s a big deal at all. If my wife wanted to go to a bar with (female) friends, I wouldn’t give it a second thought.
If she wanted to go on a camping trip with a bunch of teetotaling guys, I’d be much more concerned.
I actually find myself in a similar situation quite often, as I am friends with many single, young women who climb. My wife doesn’t like climbing. To avoid the potential/appearance of impropriety, I won’t climb alone with the women. But I will go in groups where both genders are included. OTOH, I have no problem if she plays tennis with single men.
Regardless, people will always have the opportunity to be unfaithful, so it’s not worth getting too worked up about it IMO.