I am obviously rewatching Spiderman 3 right now, and I cannot believe just how pointlessly bad Peter's reputation got tarnished by this scene.

Is it a bit cruel? Sure. But it happened already AFTER MJ left him AND she didn't even tell him about her change of jobs. He is now in a full right to find himself a better girl, as well as be obnoxious about it. She is OUT OF THE PICTURE. She has no right to demand special treatment anymore.