I finally decided...

Over the months, my wife kept pestering me about sucking another man's cock. Finally she presented an ultimatum. "Look, either you do it or I don't participate anymore. All along I've done what you've
wanted me to do and to be honest I have enjoyed it. Now I want you to do something for me. Is this so hard? I'll even give you an added incentive and suck your cock while you're sucking his. Agreed?"