Ughhhhh - NO FUN LAST WEEKS OF SUMMER

First of all, sorry I haven't been on lately!
So, for the last like 2 weeks of summer vacation, my dad has me. He says he'll be doing stuff with me, but I don't know.  Of course, that means with his girlfriend too.  I am thinking he already has plans with her.  However, I want to see his parents.  I haven't seen them in a really long time, and I want to spend time with them.  So I talk to him, and he says he wants to too, but he has to talk to his girlfriend to see if we can even go.  This infuriates me, because my summer vacation shouldn't revolve around his girlfriend.  He should also be able to spend time AWAY from his girlfriend without her freaking out and wanting to break up.  (This has been happening by the way.)
 
So, I'm left with two options.  If he says it's okay(probably won't have this happen), the two of us will go see my grandparents.(Without his gf because I don't want to spend more than a week with her).  If he says no, I will end up going to my grandparents house alone, and be mad at him for a very long time because he can't be away from his girlfriend more than 2 days.