Sounds to me like your wife is already interested in the hot-wife-cuck fetish.

Possibly terrible advice but I'll give to anyway:

Secretly do some homework on hotwife/cuck fetish, you can tell her later if it was a surprise success or totally !not!

The best way to be introduced to a new fetish is as masterbating material (you have full control in stopping it, with no power dynamics or future repercussions)

Here a great ntr game you can try:

https://hangovercatpurrroduction.itch.io/ntrd-by-clumsiness

And a great dougin

https://nhentai.net/g/460008/

And a BBC comic if your not much for anime

https://comics.8muses.com/comics/album/Blacknwhitecomics_com-Comix/BlacknWhiteComics/Slutty-Moms