I think what goes on between a man and a wife, no one from the outside really knows.
its personal its between the two of them,,
its hard to understand the life someone else leads. only double so when its a couple. not any of your business.
someone once said if your spouse is cheating and you don't have a clue, its because you don't want to know. or that is how much you care about your relationship,,
you said your sure he doesn't have a clue. I guess how close are you with this co worker,
I have had a double life for a decade, not one of my friends really know what im up to, some might suspect something others, no way would they believe I am doing what im doing.
just leave it alone.