Izuku is pushed to edge with training and is worn down my most of his classmates to try harder. One day All Might snaps at poor Izuku and takes his quirk back in jealousy of that Izuku is better than him. So after that Izuku moves out of the dorms, quite happy actually, now he and the other *ahem* 1A students can come out of their shell and go back to the way they were before.