These stories have basically the same idea: husband is thumb-sized, and wife her first BBC. What changes is the dynamic between the couple and the setting.
Ruined is the best story...4 stars. Too big was my least favorite...2 stars. No love from the wife just mean and loathsome. I did not like her and hoped the husband would just leave. There's a way to do humiliation and this was not it. Office was ok...3 stars
Decent Set of Reads Although the Trope Can Go Either Way
This is a trope that can easily get out of control for this reader's, tastes. The idea of a wife sharing situation is not for everyone, and some of these wives', methods, may be controversial. But if steam is what you're looking for, these stories are a good start.