L is for letting the negatives happen. When an alcoholic drinks, negative things happen, the may get into arguments or fights, they may have an accident, they may fall asleep on the couch and never get to bed. There can be many negative outcomes.
Much as you may want to, it is not your responsibility to rescue them from these negatives. Indeed, if you do rescue them, you may be prolonging the drinking. One of the main reasons why people change (not just drinking but anything) is that that behaviour results in negative outcomes. So, for drinkers to change they need to come to associate drinking with consequences.
This video explores this topic further.