Asking gf to not invite her cousin and best friend to our international trip?

Originally my gf and I have been talking about taking a trip together to Japan just her and I. Her and I always talk about our dreams to travel to different countries together. To get to the point, all of a sudden she tells me out of nowhere that she wants to invite her cousin and her best friend. I'd prefer it to just be her and I because the dynamic and logistics and vibes just completely change especially on an international trip. (Choosing activities, preparation time for each person, intimacy between my gf and I is affected in my opinion). Am I the asshole for asking her to not invite them?