Primer

I didn't really understand Primer and am relying on lecture today to fill me in. I understood that the two main characters built a time machine (and that they had doubles because of their going backwards and forwards in time). But what caused the Aaron to run away in the end to France and the other to stay? Did it get to a point where it was just too much for them to handle? Or is the Aaron in France the double, with the original Aaron, oblivious to time traveling, stayed back and resumed his normal life? 

I am aware that Abe used a fail-safe "box" to go backwards in time to before he even told Aaron of hm what he's found... But something seems to have backfired because Aaron is still aware of the machine's capabilities. As said above, I'm relying on lecture to fill in the missing gaps... 

Time travel is always in interesting concept to explore, and I think the director/writer's deliberate use of diction and frame shooting (although confusing) works very well with the content and message of his film.