Why doesnt he want a girlfriend & why does he treat me like this?

Well hes 25 and im 21, weve been friends for over a year. He was in a 3 year relationship that ended one year ago this past august. We started hooking up over the summer and have been since. Well he only treats me well when hes been drinking. He will text me or call me and tell me he wants to keep me, or he loves me and has to see me right away and calls me baby, babe , beautiful etc..But when hes sober, im the last thing on his mind yet he says he worries about me and wants me to be successful. I dont understand him and I dont bring things up with guys cause they cant stand it. i dont know why im so hung up on someone who treats me like this. its emotionally tiring, i need someone to make me happy and to acutally care about me..i dont know why he was in a 3 year relationship but if his subconscious drunken self thinks im so great...why doesnt his sober self??