Right. You're comparing covert extramarital sex to eating a cookie dough blizzard, but I'm naive.
We're talking about a website whose slogan is "Life is short. Have an affair.", and those who get caught using it without their spouse's consent. You can't do that and expect your spouse to remain committed to you.
Also, your google-fu sucks. You've described "polyamory", which is quite uncommon. You may have an "open relationship" with your partner, and that's cool. But it's not the topic of this discussion.