I have been officially out-nerded. Well done sir, well done.
I still don't think they were a couple in the movie, though I fully admit there was intentional sexual tension placed there, and it's quite possible editing made things ever more murkier than intended. I took the Ian interaction more to mean she was using Grant as a shield against Ian, than as an indication she and Grant were actually together.
Whatever, we've wondered far off the original point.
I'll probably see this, because... I have a 9 yo son, so of course I will. Once it's on HBO or something.