You didnt deal well with people yelling or being mad at you since you had a very traumatic childhood and this triggers the memories hard,and that was one of those days

ur bf Demetri kept on shouting at you and arguing the things over and over again which you didnt like,this triggered a memory from your past and you started tearing up

He got more frustrated and lifted his arms slightly in distress,u flinched,thinking that he was gonna hit you he looks at you in shock as he slowly realizes