Mine, princess...
Your wife is right. When you told her your fantasies, you never expected her to REALLY cuckold you. But from the moment you mentioned it to her, she reacted VERY positively to the whole idea, and even told you who she would like to cuckold you with first. Even then -- you thought she was saying that just to give you something really specific to fantasize about -- but two days later she said she had a date with him and that she was planning to spend the night with him. And now she goes out every weekend with her boyfriend, and it has been almost a year since the last time she had sex with you.
Early in my marriage I started having fantasies of my wife cuckolding me with other men. When I shared my fantasies with my wife she thought they were weird at first, but she didn’t freak out since they were only fantasies. As she grew more comfortable with my fantasies we would sometimes talk about them during sex which always made me super turned on. She loved being able to get me so aroused so easily. One day we were sitting in the living room and she brought up the subject of my fantasies and asked how I thought it would work in real life. I told her that I wouldn’t really want to do most of my fantasies in real life. For example, I didn't want to watch her with another man. Also, I didn't want to know who the other man was. I would just want her to go out on dates with other men and if she chose to have sex with them that would be ok too. I told her that I’d never want her to do anything unless she actually wanted to. I would however, like for her to tell me what she did her dates. She looked at me kind of puzzled and said “so you basically want me to have “friends with benefits”. I laughed and said “I had never thought of it in those terms, but yes that was exactly what I wanted”. My wife smiled and said, “I think I would like that too”. Nothing happened right away, but that was one of the first times we talked about actually doing something.
This is based on a real event that happened many years ago. I told my wife about my cuckold fantasies and encouraged her to flirt with other men while we were at bars or parties. Afterwards we would go home and have really heated sex. My wife loved how turned on I got from seeing her flirt.