Jamieson, Fausset and Brown on Galatians 4:16

16. Translate, "Am I then become your enemy (an enemy in your eyes) by telling you the truth" (Ga 2:5, 14)? He plainly did not incur their enmity at his first visit, and the words here imply that he had since then, and before his now writing, incurred it: so that the occasion of his telling them the unwelcome truth, must have been at his second visit (Ac 18:23, see my Introduction). The fool and sinner hate a reprover. The righteous love faithful reproof (Psa 141:5; Pr 9:8).