There is a concrete difference between the first and second half of the film, she turns from the hunter to the hunted.
It seemed that way to me too, and I ran with that during the film (for lack of any better explanation). I think only one part of that is concrete though. "she turns"
Suddenly there are a half-dozen motorcycle guys going off in different directions, and a sense like they are following her. I wouldn't say hunting, because that implies an certain intention. But we don't know what their intentions actually are because nobody says anything. Anyways, we do see the terrain changing each time the motorcycle guy is shown and it appears that he eventually arrives in the same region she is in because the weather and terrain match up, and we haven't seen him take a boat anywhere, so where else could it be? But why can't he find her? He knew where and when to find the deformed guy, with such precision he even knew to open the car trunk before before he
saw his target. That's how confident he was that the guy was right around the corner. And yet between him and his helpers they can't get closer to SJ than being in the general region? How do they even get that close? They know where she is, but only kind of? Are they actually trying to find her or are they just trying to remain close at hand to assist her as they had been before? We don't know because nobody says anything.
It's true that SJ stops her van-pickup routine. She's driving, she stops, it's foggy, she gets out, and the van is never seen again. Were the motorcyclists tracking her through the van, and that's why they were only able to have a regional sense of where she was? But then how did the one motorcyclist track the deformed man? Different method. Either way SJ leaves the van and walks to a town and tries to eat cake, which is definitely outside of anything we have seen her do before. And her demeanor has change... she no longer has that cold sense of purpose in her eyes. Instead she looks lost or vacant or in a daze. I agree. There has been a change in
her. An observable, demonstrable change.
We don't know what it means, we don't know precisely why, we don't know if it's permanent, we don't know if she will change even more, we don't know if she remembers anything she did, we don't know how far ahead she's thinking, we don't know if she feels the presence of those motorcycle guys...
Something's changed though. That's one, of a thousand things, that I will concede is able to be established. One orphaned fact.
I just don't know what's gained by
not providing answers to these questions. This idea goes around that good films are the one's that generate conversations after they're over. I hear directors say "if people come away and they're talking about the film on the way home then I've done my job". I don't get that at all. Maybe they're talking about how crap it was. There's value in confusing an audience now? If all you're trying to do is get people to talk, that's a low bar in my opinion.