Phillip is moping around because his "steady" girlfriend, janet, is going on a date with another boy she's interested in. his dad comes up to him and says, "i know just how you feel, " phillip cuts him off, shouting, "you don't know how i feel. no one knows how i feel! just leave me alone! " philip's response demonstrates a phenomenon known as

Philip is exhibiting adolescent egocentrism.
Egocentrism is a characteristic of very young children, however, it can continue into adolescence as well, as is the case with Philip in this case. He cannot put himself in other people's shoes because he is experiencing pain and believes that no one else has ever experienced that as well. He thinks no one can understand him which is a classic example of egocentrism - focusing on oneself.