The story that introduced me to the cuckold stories and for me is still a gold standard is
Neighbor Chronicles
https://www.literotica.com/series/se/281613767 by AvidReaderNoviceWriter
Unfortunately after a stint on patreon he stopped posting luckily Writerinabox stepped in and and finished the series which can be found here
https://www.literotica.com/series/se/494088906
Although yes the series features a well endowed antagonist , the husband isn't too small and the wife loves him.
i have just started reading a 4 part sequel by RolePlayLiterate (Pseudonym for Vivian's Valley) which can be found here
https://www.literotica.com/authors/RoleplayLiterate/works/stories which dives deeper into the cuckold fetish.
The other gold standard is slipping into depravity found here
https://www.literotica.com/series/se/494209119 . The cuckolding happens between chapter 12 -19 the series then continues with the antagonist continuing to try and come between the married the couple and destroy the marriage unbeknownst to them.
From what I have been reading on here once the series gets to a point the sex scenes become less interesting. its the drama that continues and the reader is left just wanting to see the wife get her comeuppance or the husband take back some control. slipping seems to still be exploring the wife's descent so the sex is still well done while we wait for the truth to come out and wondering if it will be too late as implied in chapter 1. Series is up to chapter 46 with the writer posing roughly fortnightly