Hubby wants to share wife with other men Wife really not interested.Eventually wife agrees and dumps husband for new guy.Husband is devastated, but too late. Divorce occurs and regretful husband leaves on cross country motorcycle trip .Wife regrets divorce and tracks husband down in Key West/
A lot of similar but reversed details:
https://storiesonline.net/s/23951/wheres-buster-redux
Wife chooses to cheat, husband takes off to Key West on a boat. Wife tracks him down seven months later to reconcile, he wants a divorce.
Another similar but not the same.
MC's wife cheats for a promotion. MC leaves, ends up in Key West, meets his ex there.
https://storiesonline.net/s/27537/all-my-loving
Not the one you want, but Mypenname3000 has dozens of stories focused on mind control, body modification, and incest.
Many follow a pattern of husband wants wife to be more sexual, introduces some magic item that turn her into a bimbo, much sex ensues. Daughters are often added in and harems are common.
Note that while there are over 200 stories posted here, this isn't the full library. The author also has more stories (or, in some cases, alternate versions of stories) on sites without the under-14 rule.