I was 21 and married. With my encouragement, my gf then wife, was fucking friends of mine while I either watched or joined in. At first I just enjoyed playing with and fucking her sloppy-seconds pussy. I eventually began eating her pussy after other guys fucked her, but I was embarrassed about my behavior, so I always waited until the guy who fucked her left.
I eventually got over my embarrassment and started eating her pussy right in front of whoever had just fucked her. I realized that seeing me do that turned some guys on. After eating the cum of a dozen different guys who were each fucking her, I realized that actually sucking a dick was not such a big leap.
One night she was lying naked on the bed making out with a naked friend of mine who had been fucking her for about year. I was eating her pussy while they kissed. His cock was semi-erect and just sort-of waving in the air near my face. I just leaned over and slid my lips over the big soft head of his dick and started sucking him. Fortunately, my buddy did not object. I started sucking his dick every time he come over to fuck my wife. I eventually began sucking the cocks of some of our other friends who were fucking my wife.
Rob