My wife has had several "affairs" with men she has worked with. One was with the son of the company's owner. It began innocently enough, office flirtations, then lunches. The company sponsored a co-ed softball team, and he recruited my wife to play. As her spouse I was grudgingly invited to join the team also. After games we would all gather at local bars. We usually couldn't stay late, as we had a babysitter at home needing to get up for school the next day.
One evening I offered to let her stay while I'd go home to allow the babysitter to get home. She eagerly accepted, telling me she'd get a ride home with someone from work. I finally heard her sneak in at...FOUR a.m! I pretended to be asleep as she slipped into bed, and yes, I could smell the sex on her. When we got up for work three hours later I said I'd gone to bed at 11 the evening before and asked what time she'd gotten home. She said "Ohh, around midnite I think." LIAR! I checked her panties in the laundry later and found the crotch stiff with dried sperm! Full disclosure...I jerked off with those panties before I left for work.
After that her work schedule seemed to shift a bit. She'd go into the office earlier, or "need to stay later" more frequently. Our sex life became less frequent, though I did really get off when I could feel she was slightly gooey from his jizz. She'd pass it off as being extra excited, and that was fine with me. After a few months she announced she was pregnant with "our" third...