AshleyMadison.com and ArrangementFinders are two websites that cater to married people and those interested in finding married people. OkCupid is another site that may have men interested in married women.
As of 2015, AshleyMadison and ArrangementFinders are free for women to join. Both sites boast a wide variety of users and promise complete anonymity. Each site allows users to set up a personal profile and message other members,
OkCupid does not cater specifically to married people, but it does have a space in its profile to specify the user's marital status and what type of relationship she is looking for. OkCupid is free for all users.