When someone does not care how it effects the relationship or the person they love...that's a problem. "It's just how I am" is another solid sign that they are not able or willing to let it go. I've been there.
I'd try to find out her history with drinking/drug use in the past...there may be a dependence issue. It needs to be handled very carefully... for someone dependent, if alcohol is removed many times something else just gets put in its place...have to make that some kinda good hobby/pastime.
For some at that age it's the party girl/guy kinda winding down but for MOST as life gets more difficult the drinking gets worse with age...it's a coping mechanism and deters true connection with others which honestly is much of the reason for the drinking in the first place.
I'd try to find out her history with drinking/drug use in the past...there may be a dependence issue. It needs to be handled very carefully... for someone dependent, if alcohol is removed many times something else just gets put in its place...have to make that some kinda good hobby/pastime.
For some at that age it's the party girl/guy kinda winding down but for MOST as life gets more difficult the drinking gets worse with age...it's a coping mechanism and deters true connection with others which honestly is much of the reason for the drinking in the first place.