How do i tell my best friend i want to hangout with HER and not her bf all the time?

I'm graduating from beauty school tomorrow and i wanted to go to lunch with my best friend after she see's me at my little graduation. Of course shes bring her boyfriend. I don't mind hanging out with him but i feel like tomorrow should be about me and i should be able to spend time with my friend and not feel like a third wheel. What do i do?