relationship crap

So I have been with a guy almost three years it has never felt secure I feel like I’m just there when he is lonely he chooses weed and his friends over me he sees them more than he sees me and he also told me his life doesn’t revolve around me. He is 33 years old and I am 25, he is only nice to me when he wants something, and all I ask for from him is a bit of communication but even that seems to much for him why can’t I leave this jerk