Approach her slowly and don't pressure her to much, engage her mind, peak her curiosity, ask her if she ever thinks about being with another man, how exciting and stimulating it would be to have sex with him, keep engaging her in sexy conversations, ask her if she remembers having first dates and how excited she would get going out with someone new, take her out for drinks and have her play a game picking out a good looking man and describe how she would seduce him and how she would enjoy him. Keep her thinking about the thrill of new sexual experiences. Give her time to picture herself having sex with someone new, let her mind guide her direction and constantly reinforce her self confidence, compliment her, tell her how sexy she is, how desirable she is. Tell her that there are lots of men who would love to be with her, ask her why she should deny them and herself the thrill and pleasure of new sexual experiences, think of it as starting down a new a new path that will be fun, exciting, and could be very satisfying! She's a woman with a lot to offer, tell her don't hold back, go for it and dive into a new world of fantastic sex, explain that it will improve your sex life by keeping things incredibly exciting, interesting and providing experiences she would never have had if she didn't try something new. It could be very rewarding and alot of fun. Just think about it please. Tell her you're there if she has questions or just wants to talk and you promise not to get jealous of her being with another man, in fact it will be a real turn on for you to see her take another man, especially if he has a really big cock, this is an adventure the both of you should explore and enjoy together. Please give it a chance to happen.
In most cases convincing your wife to enter into the Cuckolding lifestyle is a waste of time. It has to come from the wife and I'm not saying it hasn't been done/happen, but the odds are long. Remember swinging is the gateway to all sexuality.
Break it down:
Is it about her having sex with some else?
Is it about making you subservient?
Is it a one time event or on going?
Is it just role play or sex talk?
You need to know what is it about to go further. It will determine your path.