It's not just "close one eye" while you go out and play, and it's not just 3p or swinging either. It's your SO who enjoys seeing or even thinking about you bonking others without participating. Even if she stays at home, she gets wet thinking about you bonking others from FL Dome. If she's watching, she might even enjoy being tied up and helpless to stop you. You can still bang her as per normal after, she also gets off thinking how many holes your cock has been into
Obviously this is extremely rare and a dream come true for many men haha. I just wished it was a bigger kink for women...SO many men have cuckold fetish. I've read that open marriages often doesn't work because one party gets jealous when the other has more sex, but for cuckolding there's no such disparity issues.