How do I get him to love me again like he once did?

Okay so here’s the story from beginning to end… I went to Florida this summer to visit my family. We start hanging out with her friend and her friend and I start to get feelings for each other before I know it we are boyfriend and girlfriend. After some weeks he starts tellin me how much he loves me and how much he wants to be with me and that we are gonna be together forever because we are so perfect together. After a few more weeks I started sayings things like that to and we were getting pretty serious. Then I went back home and we tried to have a long distance relationship. We shortly found out that it wasn’t going to work and we broke up. But he promised me that he would always love me and that we would be together in the future. I recently found out that he and one of my more distant cousins were going out. She knew how much we liked each other and this is completely against the “family code”. My cousin who introduced us even said it was wrong. But the boy tells me it was she forced them to go ut which I completely dont believe. I don’t know who to believe and who to be mad at. All I want is for him to love me again like he once did because I havent completely moved on yet..