Why do i keep pushing people away?

i am 16 and my parents are divorced. i am always cold and distant to my mom and stepfather who i live with because i blame them for what happened. but lately ive been pushing away friends too. its like i get tired of them or something. especially guys. i let them in and become really close. i tell them anything they want to know. then after lke a month i move on and stop talking to them. its almost as if im only really interested in seeing if i can get them to lke me. like a game. i dont understand why i do this? because in the end i not only hurt them but myself as well