He had to enter into an agreement with her. He had to stay away from her place of work, church, school, etc. He couldn't come within 500 feet of her parents home, etc. And the allegation isn't that the phone hit her after being slapped out of her hand. He broke her phone and after she got mad he slapped her in the face. He threw her into a closet after she didn't text him back fast enough. He allegedly threw her onto the floor another time for apparently not spending enough time with him. She got a laceration on her knee from being thrown down.
That's just issues with her. He also was accused of assaulting a guy in a bar because the GF was talking to him. He smashed her windshield in another allegation and also bent her key so she couldn't get away from him.
We aren't talking childish, college stupidity here. We are talking about real issues. The fact he had to enter into a restraining agreement should tell you that these are very serious things, not college kids being college kids like some are trying to argue.