“Bahurim.” Ancient Bahurim was just east of Mount Scopus, which is just north of the Mount of Olives and connected to it by a lower saddle between the mountains. Thus, Abner had given Phaltiel plenty of time and miles to deal with reality and return back home. In another mile or so, immediately south of Jerusalem, Abner would leave the tribal area of Benjamin and be in the tribal area of Judah where the locals might not be so friendly, so he told Phaltiel to go back home. Abner had another 30 miles or so to reach Hebron, so he was still more than a day’s march away from David.
“And he returned.” Phaltiel would have been killed had he not left, and he knew that. Abner would never have let him jeopardize the reunification of the tribes of Israel, and besides, he was not legally married to Michal anyway.