By now, every secret is out in the open, as a confrontation between Abe-2 and Aaron 3 brings both parties up to speed. They discuss the price of traveling so far back, especially for Aaron-3, who is most exposed to the boxes, explaining why his ears begin to bleed. Abe feels guilty about Granger’s condition, which was caused by Aaron-3’s anomalous presence (being the person who has traveled back the most in time). As temporal symmetry has been broken, the alteration of history at the birthday party by Aaron-2 in his timeline is null, leaving it up to Abe-2 and Aaron-3 to prevent her ex from endangering Rachel and making sure he ends up in jail.
With this common goal, the two work together at the party to “reverse engineer” a perfect opportunity to de-escalate the situation and ensure that the dude is behind bars. They succeed, but it is never specified how many tries it takes for them to do so, as Abe-2 has to factor in his presence now (as he was absent in the original timeline) and Aaron-3 has to repeat conversations while changing things enough to usher the desired outcome. Once they succeed, Abe-2 and Aaron-3 have no reason to cooperate, as their bond has been irrevocably broken — while Abe wants to go back in time and prevent everything, Aaron wants to start a new life.
In the end, the two decide to part ways, where Aaron-3 decides to leave by stealing Aaron Prime’s passport (who, by the way, manages to get out of the attic), while Abe-2 decides to stay back and secretly monitor everyone including Kara and her daughter, to make sure nothing bad happens (while Abe Prime also escapes his confines).