Wisdom would be him acknowledging that they were kids and kids do mean and stupid shit. They both grew up, she realized she was wrong and tried to apologize.
Is that the case though? Just because she apologized doesn't mean he has to forgive and forget. No one is obligated to wash away past history like that just because they
feel remorseful. From the looks of it he's moved on and just doesn't want to associate, it's pretty presumptuous to have most of your interactions be cold and negative then expect restitution after merely stating and acknowledging your misdeeds much less a complete 180 into a relation with intimate affections.
Had she gone out of her way to properly engage in making amends and slowly working on creating a clean slate that could lead into a hopeful romantic conclusion that would have been the wiser and more redeeming action. Though admittedly he didn't need to throw milk, ultimately, he never owed her forgiveness either. His actions were petty, but his logic is sound and just. She was being naïve and selfish.