GF and I are heading to a wedding next month. It's a couple she knows getting married - I've met them once or twice. I don't know anyone else at this wedding.
The other day, her friend called to check if he 'should also change my name on the guest plan,' at which point my GF admitted to me that, as a joke, she had RSVP'd using her last name for both of us, meaning it would be visible this way to other guests on the name tags at the table, and perhaps on other things.
I was pissed off with her, and said I didn't think it was funny, and she shouldn't have done it. She was upset, thought it was a funny joke, said that I was overreacting, etc.
I'm aware that it could be funny, if you know your partner likes those jokes. We joke with each other about taking each other's names when we're married, her joking that I should take hers, etc. But for me, this feels like a big overstep.