A predicament

I heard a phrase a few years ago, when I met my wife actually. I explained that I am often uncomfortable when I’m naked as I lack the size to be confident. Her response immediately set me at ease. “You’re a grower, not a shower,” she told me. I may look small, but after a bit of inspiration I have a good size (7” length, 4” around). Since being together, my confidence has grown immensely. I am now comfortable with my own body. I understand that a well groomed man appears larger (and cleaner of course) so I keep the hair short. I am able to bring my wife to orgasm and I can go for a good long time. Now I have a problem. I have a cuck fantasy. The problem is that I am perfectly capable and she doesn’t see that she could find better. We are a good fit. I know this. Her experience with well endowed men is that they rely too much on their statistics and lack any good technique. She’s not a prude and has previously expressed an interest in the cuck fantasy, but the talk breaks down when it comes down to my “inadequacies”. I am confident enough to not take her “small dick” comments seriously. I know full well that I can please her as well as any “real man”. So how do we proceed? Answers on a postcard...