Why did John White leave the colony at Roanoke in 1587?

In short, John White was forced to abandon the Roanoke colony because the settlement was running out of supplies and could not be assured of resupply from England.
As summer neared its end in 1587, John White found himself and his fellow English colonists in desperate straits. On August 8, he had mistakenly attacked a group of Dasamongueponkes. He had thought he was leading an attack on the tribe that had killed the first Roanoke settlers. However, he and his fellow Englishmen had blundered into the wrong village. This was a group of previously friendly Native Americans. After this, relations between the two groups rapidly fell apart.
To further complicate matters, without Native allies, White's settlement would be completely reliant on resupply from England. However, the chances of resupply were very much in doubt. White's colony had not originally been headed to Roanoke. When they left England they had been intending to establish a colony in the Chesapeake Bay. They were dropped off at Roanoke at the insistence of their Portuguese navigator, who refused to take them to their intended destination. As a result, White's colonists were uncertain as to whether or not resupply from Europe would reach them before their stores of food ran out.
White did not want to leave his colony. However, his men were adamant that they leave in order to secure supplies themselves. The prospect of facing the coming winter without supplies or Native allies was too dire. In the end, he had no choice but to leave. White and his men felt it necessary that White go to England himself since he had enough influence and resources to more quickly procure supplies.
White left eighty nine colonists behind with the plan to quickly return with necessary provisions. However, the threat of the Spanish Armada delayed his return for almost three years. By the time he was able to get back to Virginia, he found his colony mysteriously abandoned.