Alcoholics Wanting Someone to Drink with

Thank you for your question. I can't say I know what any particular person may be thinking. However it seems logical that an alcoholic person who wants his girlfriend to drink with him might want to legitimize his own drinking. He may be thinking that if his girlfriend drinks with him, then he isn't doing anything wrong. So his girlfriend drinking with him would help him to alleviate any guilt his has over his own drinking. Someone who has a drinking problem can be aware deep down that they are harming themselves but he may be unable to stop. When you know you're doing something wrong, you feel guilty about it. But if someone joins you in this behavior which you feel guilty about, it can make you feel less guilt about it. The alcoholic person can justify their own drinking by thinking, "my girlfriend is doing too so it must be OK." 

 I hope this helps answer your question.