If he cheated on you once he will definitely again

Me and my ex have being going around for past 8 years. We know each other from childhood. Had been to same school, High school, Undergrad school. We r not from states. He came to states 6months before me. I came here just for him. Two years back he cheated on me but I forgive him now after a year again he cheated on me with the other girl. I don,t know what I did wrong he just says it,s time to move on.. I don,t like you the way i like you before. I am changed.. I have no idea..he knows that I am here just for him but again he didn,t think of me ..Once a cheater is always a cheater..I shouldn,t have given him a second chance.