I’m certainly not an expert on swingers, but my impression is that swingers have rules governing how this sort of thing goes precisely so that your spuse isn’t boinking random strangers and bringing an STD epidemic back home.
A lot of couples are able to work things out after adultery, but “I got to close to someone at work” or “He was an old flame from high school” is on a different planet entirely than “He came over to fix the dryer and I boinked him without even checking his name tag.”
Swingers do have rules but the nature of the beast is not conducive to exercising the self control to follow those rules.