Why do I keep forgiving him?

I really like this guy , I’ve liked him for a while . He likes me too . But he’s always hurting me . In the end I’m always forgiving me because I can’t stand being mad at him . And no matter what he does I still want to be with him . Recently he got with one of my friends and told me he only got with her so she wouldn’t break us up and when he broke up with her that we could be together . I’m honestly not sure if I could believe him with what he’s saying , well I’m scared to believe him because I really don’t want to get hurt again . I’m always forgiving him and going back to him . He tells me loves me and if something happens between us he trys his best to fix it and he does all this stuff for me . I know he does care for me , but I’m not sure if he does as much as he says he does . At one point I was convinced that maybe he did love me . It was always hard for me to because I always thought that he was just caught up in the moment because he’s been with so many girls before . Honestly , I know that I really do love him . No matter how young I am . I’m positive that I do . Just I’m sure if I can trust him with loving me . Should I believe what he says ?