First - it is NOT you. It has nothing to do with your physical appearance or sex appeal (we are so conditioned to believe that somehow WE play into these issues, huh? hugs...) There could be two reasons. If he is still actively drinking, it could be"brewers droop" when a person is so intoxicated that they can't achieve or maintain an erection. As an A progresses through alcoholism, it takes less to cause this to happen. If it is not only occurring when he is drinking, it could be alcohol impotence where, after years of alcohol abuse, a man's nervous system is so damaged that the connection between the brain and genitals no longer functions properly.
If it makes you feel any better...I know this because I had the same questions. (((hugs)))