Sadly, in my experience yes this is 'normal' behaviour for an alcoholic.
Once they see you may be pulling away and have had enough they will turn on the charm, maybe stop drinking for a period, but unless they are fully embracing recovery the cycle is pretty much as you described above and will continue.
Whether they turn on the charm for fear of losing a person they love, the enabler they have, or a mix of both Idk but either way it doesn't matter if it's the same continuos cycle and it isn't a healthy place to be in.
Sorry you are going through this. Hugs to you.