It depends. Usually, I can adapt pretty easily and I can feel comfortable using the other name, but there are quite a few exceptions. It’s especially easy if I frequently hear other people using the other name. For instance, my exboyfriend’s mother called my ex by a different name than he used at school (we met in high school). Once I was around her enough, I used both names equally. He is both names to me.
Also, if the person tells me early on the name he prefers, say within days or weeks of netting them, it’s fairly easy to adjust. Also, nicknames seem pretty easy for me to adjust to. Like if it is a short for their name. Meg for Meghan, Liz for Elizabeth. Even if it’s totally different like Skip and the person’s name is George. For whatever reason if it’s an obvious nickname I adjust fast.
Here are the times the transition is more difficult for me:
A person much more senior to me who I have addressed formally by their last name for many years now requests I call them by their first name.
A complete name change and it’s night a I test nickname. If I knew someone as Joseph for years and he changed to Michael, that would feel a little odd to me.
My BIL changed one letter in his name to sound less Mexican and more European. That sort of bothers me, because I think it shows his insecurity, and I think no one really thinks anything about his given first name. I still call him by his given name, his whole family does, except his husband who has always known him by his business name. He has never asked me to use the other name. I thought about asking what he prefers, but I just leave it be. Calling him by the other name would feel a little weird.
If I met jellies in person I would expect to call them by their real names and it wouldn’t be weird at all. I don’t mean expect like I’m insulted if they don’t want to give their real name, I just mean I wouldn’t have a problem adjusting.
I call me husband four different names and I don’t think twice about. His full name, his shortened name, and two other nicknames.