Say for example my name is Annabel (it's not, of course), but I'm known as Anna. I've been known as Anna since being old enough to express a preference. The majority of people don't even know that my 'legal' name is Annabel. However there are some organisations (e.g. in emails from the HR department at work) which insist on addressing me as Annabel as it's my 'legal' name. I hate this!
I have no problem with the name Annabel in principle. However I don't wish to be addressed by this name. I don't relate to this name at all - my name is Anna.
So, WIBU to change my name by deed poll to Anna so I never have to be addressed as Annabel again?
My DM may be upset by this (she loves the name Annabel) but I wouldn't tell her and see no reason why she'd ever find out.