We'll call this girl M. I've been seeing M for a few months and recently she's mentioned tickets she has for an upcoming concert. Apparently M received for her birthday last year during which time she had a bf. She has only mentioned the concert casually and has not said who gifted her the ticket nor who she had planned to go with (this person has the other ticket). I asked if she was going with her sister, she said 'no' but gave no further answer. I'm seeing her this weekend and intend on casually asking who she's going with, my 2 questions are:

1: My gut tells me she's going with her bf from then. She's usually pretty honest (as women can be), how do I react if my gut is correct? Should I just stand up and walk out from whatever we're doing? Do I offer to drive her back home with no explanation? Do I say something?

2: The concept of downgrading girls to plates is commonly heard, but how exactly is it done? Is it text strictly for logistics, meet strictly to fuck, then leave? And if so, what happens when the now plate notices the change and brings it up?