need help , advice ??

Well i know not best place in the world to ask for advice but i know there people serious here so I wan to ask for advice ...
everytime i get new girlfriend first i am excited that girl is my girlfriend talking with phone , msgs , fb ... go out for dinner movie ...) but the problems start after awhile and/or we make out ( if she virgin and don't wan to lose it ) or have sex ( i don't force any girl to do something she don't wan or not comfortable with it ) after couple of days week max i feel kind bored of here and don't wan to b in relationship and wan to b single so i start to think of something to break up with here , don't talk with here on phone or answering the phone .. or go out ) avoid here ,until all connection cut and i desepear don't talk with here anymore so i go back single again after week i feel bored then so i wan relationship , i see new girl (college/club/street/coffee shop...) and i like here , i go ask here to go out with me for date and then same thing happen again and met new girl and happen again ....

i am Confused and don't know wt to do , seriously i don't wan this but is happen , i got that one life opportunity girl more than once and let here go any help ??

other information dunno , nothing on my head for now , ask me wt u wan to know .