You are not alone. Actually, now you are.
Bug 330884 – When different users on one system choose to save or not save passwords for sites, any other user can see sites they not only saved passwords for but can also see what other users have been saving/never saving passwords for.
Says the user who first reported it: “This privacy flaw has caused my fiance and I to break-up after having dated for 5 years.” (I assume at some point earlier in the five years her fiance had gotten past the grammar thing.)
A commenter on the Bugzilla website writes, “There is a button under Tools > Options > Privacy > History. On the History tab, I believe, you will see a button for ‘Erase My Relationship’ …” Ouch!