“Now when Paul and his company loosed from Paphos, they came to Perga in Pamphylia: and John departing from them returned to Jerusalem.”
King James Version (KJV)
13:13 John withdrawing from them returned - Tired with the fatigue, or shrinking from danger.
Ac 13:13 Now when Paul and his company. Henceforth Paul is the leader. From Paphos they sailed northward to Perga on the Asiatic mainland, an important city of Pamphylia. John departing. Why he left we do not know, but we know Paul did not approve of it. See Ac 15:39. Perhaps he feared the dangers before him.