as the girlfriend of an alcoholic...well, lying and hiding go hand in hand with it, so there's no use teasing apart the drinking from it...because in a short time they are wedded.
My BF avoided me, broke dates, made excuses so he could stay home and nurse his beers instead of do anything with me.
I am a recovering addict, and my boyfriend stopped drinking a couple months ago, and we've had the "why lie" discussion.
our own sense of guilt and discomfort about our behavior, wanting to not deal with people's reactions, throwing others off our scent, because it becomes habit, so we can kid ourselves that it's not that bad, another way to isolate
towards the end of his drinking, he flat out told me "I really would just rather go home after work and get drunk then spend time with you."
ouch.
I didn't react well
that's why we lie, because people just aren't going to understand that pretty much our only priority in life is getting drunk and wasted. We don't care about them, or us, or family, or job, or promises, or holidays, or dinner, or movies, or anyone's bothersome feelings except our own. We just want to get drunk and wasted and to be left alone.
Since we feel crappy saying that, and they get P'd off hearing it, we make up lies instead. No one believes them, but at least they sound better than the truth.