> Your old name is just for her to use, in intimate situations

She already said it's fine if her girlfriend uses it at home but she is still using it at industry events and during interviews. I'm not sure trying to wrap the exact same suggestion in some more flowery language is going make any difference.

OP offered that solution and she didn't want to do it and is now sabotaging her professionally. I would have trouble getting used to it to but it doesn't seem like she is willing to do it. It seems like your suggestion has already been tried and failed.

Edit: typo