Do drunks really forget what they said the night before?

My boyfriend is a professional, a gentleman and treats me wonderfully. However if he gets drunk he will say mean things like "I can't believe I go out with a @#$% like you" and "I'm going to leave you and go out with all the women I want!" The next day when I tell him these the things that he said he swears he doesn't remember saying it. He does apologize and things go back to normal. I don't drink so I have never experienced this. Has anyone out there had this experience themselves or with someone else? Why would he say those horrible things to me? Does he really mean it and use the drunkeness as an excuse? This doesn't happen often, and he usually treats me like a queen. Do they really forget? We are not kids, I am 45 and he is 54.