ויאמר אסתירה פני מהם אראה מה אחריתם
"And He said, 'I will hide My face from them. I will see what their end will be” (32:20).
Contrary to popular belief, hester ponim does not mean that Hashem removes His Providence, abandoning us to the mercies of others. G-d forbid to entertain such an idea, since Hashem promised that He will never remove His kindness from us. When He is in pain, we are in pain. However, based on our deeds and situation the ways of Providence may change so that instead of a revealed Divine providence Hashem puts in place a concealed Providence in which His love for us is less obvious.
Rav Shmuel Bornstein of Sochotchov compares Hashem's conduct with the Jews to a father teaching his son to walk on his own. The father hides from the son in order to get him to run after him and take steps on his own, without any assistance. He watches his son's steps from a distance, and as soon as he senses that his son is going to fall, he immediately runs to him to support him. Similarly, Hashem says that He will hide His face from us, so that we will have to look after ourselves without Divine assistance as it were, but Hashem will “see what their end will be”: He watches us in order to straighten our ways and guide our actions. (R' Moshe Sternbuch)