By design, the nickname on the site is immutable, since it would be a huge source of confusion for people if the names of their correspondents suddenly changed! However, if there is an exceptional case, or you've only just logged in for the first time, or if the change is just a typo, please ask Cupid, and he will manually change it for you in the database.

Normally, the only way to change your nickname, is to deleting and recreating your account. If you are going to do this, we suggest you take a copy of your profile and any messages that you want to keep. Also, we'd advise you to mention this to your correspondents.