Unlike some of the time-travel movies I love like 'Primer' or '12 Monkeys ' 'Looper' is not about time travel. It's about this situation that time travel creates and the people dealing with that situation. So narratively the big challenge was to have time travel get out of the way.
I think of marriage as a garden. You have to tend to it. Respect it take care of it feed it. Make sure everyone is getting the right amount of um sunlight.