"The Evil Dr. Meinclare" is one of my favorite AR stories of all time. Seeing the husband and wife interact at a variety of different mental ages hits a lot of buttons for me: both as mental kids thinking it's gross to sleep together ("girls have cooties!"), the wife as a teenager trying to convince her kid husband to give up the information, the wife as a teenager "breaking up" with her husband when a hotter high schooler comes along. Everything is perfect.
Are there any other stories that have this kind of interaction?
(I do know of at least one other similar story: the movie Monkey Business (1952). That also features the husband and wife as kids, but it's not as "fetishy.")