sexually frustrated!!!

soo me and my boyfriend been together for 4 years now & lately for the last past few months we haven't had sex. I'll ask him can we and he'll tell me yea, but end up not or he'll be on his game or just go to sleep.. and I'll being it up to him but it never gets no where .. I'll watch porn instead to help my need . idk what too do ? i never cheated in my life but man I'm not getting it from my boyfriend & it's gonna push me to go find it else where .... help!!!