Favorites list can be cleared due several reasons, and the most common are:
1. If you have added lady's profile to a blacklist then she will not be able to write you new letters only after 24 hours after adding to a blacklist. Old and received recently letters will not be deleted;.
2. Lady cannot be in My favorites and My Blacklist simultaneously;.
3. If lady from you Favorites list was deleted from a website, then she will also will be deleted from My Favorites list;.
4. If lady from your Favorites list was added to My Blacklist, she will be deleted from My Favorites list.
5. If lady from your Blacklist was deleted from a website, then she will also be deleted from My Blacklist;
6. If you will write a letter to a lady from your Blacklist - she will be removed from My Blacklist.
For more accurate information please read this article
If the mentioned reasons are not the one that caused your lady to gone from the list, please contact website's technical support immediately.