Can someone help me, boy problem!!?

long story short i was suppose to go out with this guy went away for seven weeks came home with a boy friend broke his heart he got a girlfriend we both broke up with our boyfriends or girlfriend in his case and i want himn back but i dont know how i can win his trust back... in need help and he always like flirst wih me when im by him alone just not with his stupid friends...help please!