True, his thoughts are all over the place. He's going through a rough time in his life, trying to figure out who the hell he is and what he wants out of life away from Cersei.
I don't think he will be able to have anything with Brienne until he has closure with Cersei. I mean, when you love someone that completely, where your whole life revolves around those feelings for so long, you can't just leave it behind that easily.
These last two books are seriously going to be packed. I have a feeling it's going to be 8 books...FML