This is a very difficult situation. First, you should have an open and honest conversation with your wife. Try to understand why she has such thoughts. Maybe there are some problems in your relationship that need to be addressed.
A 'cuckold' usually refers to a man whose wife is unfaithful. So'my wife is my cuckold story' might imply that the story of their relationship is centered around the idea of the wife being unfaithful, or perhaps the man's perception of it, but it's a very strange and ungrammatical way of expressing it.
Here's a story. There was a wife named Lily. She was very outgoing and made friends easily. She met a new neighbor, Mark. Mark was charming but not entirely honest. He started to give Lily a lot of attention, more than a normal friend would. Lily didn't realize it at first, but her husband, Tom, noticed. As Lily spent more time with Mark, Tom felt like he was being pushed aside. It was like he was becoming the cuckold in their relationship, even though Lily didn't have any improper intentions.
One possible reason could be a lack of emotional connection in the marriage. If a wife doesn't feel emotionally fulfilled, she might be more likely to seek that elsewhere. Another reason could be a mid - life crisis, where she might be looking for a new sense of excitement or adventure outside of the relationship.
Yes, in some classic literature, themes of cuckoldry can be found. For example, in some Shakespearean plays, there are elements of relationship complications that could be related to this concept in a more veiled way. However, it is not a very common straightforward plot, as it often involves complex emotions and social taboos.
If he's comfortable with it, he can just go for it. Maybe start small, like trying on a piece of clothing. But if he's not, he should communicate his feelings clearly to his wife. He can say something like 'I love you, but this isn't something I'm interested in right now'.
She might mean that she wants you to stop her from sharing a particular story. Maybe it's something embarrassing or she just doesn't want it to be told further. So, it could be as simple as you agreeing not to mention it or reminding her not to tell it if she starts.