My son 5 year is very obsessed about 1 friend of same age. when that boy is not around he plays with everyone he is creative but when he finds that boy, he doesn't listen to anyone but keeps following him, copies him. he doesn't play with anyone else. if that boy says you don't know to play he moves to a side. it's like complete obsession about that boy. I have tried convincing him, talking to him avoiding him..no use...is this normal.