This has come up several times over the past couple days -- when that happens I sometimes think Someone is trying to tell me Something...
When I set a boundary, it's very easy to have the unconscious expectation that because I have powerfully/forcefully/warmly/strongly/kindly/clearly/heatedly/whateverly set that boundary with someone that they will now, having been served notice of the consequences of their actions, change their behavior.
But that's making the boundary about an expectation -- and that's a really, really bad idea for an alcoholic, since expectations are usually midwife to my resentments.
What's best for me is to remember that the boundary is about communication. If you do this (or don't do this, or whatever) then I will do that (or not do that, or whatever).
In short, it's about what I will do, not what the other person will do.
Remembering that helps me set healthy boundaries without the set-up for a resentment built in.