What is hector “ main “ fear about going back?

The main fear was public shame and distrust. His lieutenant Polydamas advised him to retreat the Trojan army before Achilles return to the battlefield. Hector , out of zealousness, rejected the advice. Then when Achilles called him for duel he gave it a second thought. Here's it : But his proud thoughts were troubled: ‘Alas, if I retreat through the gate, to the safety of the wall, Polydamas will not be slow to reproach me, since he advised me to withdraw our forces to the city, on that fatal night when Achilles re-appeared. I refused, though it may have been better! Now, in my folly, having brought us to the brink of ruin, I’d be ashamed to hear some insignificant Trojan, or his long-robed wife, say: ‘Hector has brought ruin on the army, trusting too much in his own right arm.’ If that’s what they’ll say, then I’d be better by far to meet Achilles face to face and kill him before returning to the city, or die gloriously beneath its walls.

Besides, he was tricked by Athena to stand his ground. She appeared as Deiphobus, who offered to stand against Achilles with Hector.