I am having second thoughts about my boyfriend. What should I do ?

My boyfriend and I have been together for 2 years now after 7 months of dating he met a nex girl through his cousin and they went to a club after a month of knowing each other and had sex he told me it happen because they were drunk and also he was not sure if I was serious with him then he promised it will never happen but he and the girl continued talkin and 3 months later that same girl introduced him to a nex girl and he went out with her for 1 day and all they did was kiss. I forgave him again and after that 4 months later the first girl left home and came home by him for the weekend she said she need help and he told me she forced him to hav sex wit her again but he did not mean to hurt me. After that they eventually stopped talkin but he finds I am not all that loving with him and he will start to argue with me what should I do because I really love him