Why is Shinji strangling Asuka at the end?
We don’t know how long either of them were there on the beach, we don’t know how long Shinji may have been alone in the world, and we don’t really know if Asuka just happened to materialize during that scene, or if she had returned sometime earlier. At any rate, if Shinji returned to an empty world, even if for a few days, the feeling of being the only person left in the world can be a very disturbing though. With Shinji, that thought would be even more disturbing, especially if he began to blame himself for TI. We’ve seen how fragile both Shinji’s and Asuka’s psyches can be. It may not take much to push Shinji over the edge, into a state of mild psychosis. Anno does give some clues that Shinji had been back on Earth for some time, but there’s no solid evidence to show how long he’d been there. And we don’t see Asuka return per se, so she may have been with Shinji for some time. (Posted by Vaughn L.