What is Matt's deception?

Matt pretends to miss a turn that brings them to a dead-end street which seems to be the edge of a campsite with a trailer. Matt takes Camelia's cell phone and throws it out the window. In an instant, Camelia knows that Matt has lied about Ben. Matt says he just wanted to talk to her, and questions as to why they broke up. Matt tells Camelia that he has been following her, and that she is a selfish bitch for flirting with other boys, and that Ben will be blamed when on one can find Camelia.