Amy and Nick are still pretending to be happy, when in actuality, they're plotting to destroy each other with their His and Hers Tell-All Books. Amy can hear him typing and has even tried to hack into his computer so she can read his story, but Nick's gotten smart—he's changed all the passwords and made them totally impossible to guess.
Amy knows that all his efforts will come to nothing, though. That "precaution" she mentioned awhile back? She took it. But we still don't know what it is.