Why is this in relationships? I thought perhaps someone had just found out that their dp was actually a troll!
Trolls come in many varieties - you have your harmless ones that just want a laugh, the annoying ones that want you to guess who they really really are (like I'm arsed!), the ones who are too embarrassed to use their real names and the ones who just want to shit stir and cause trouble.
Basically if you change your name to a temporary one for whatever reason, they you are officially a troll.