I was in a relationship like the one you described. I was willing to overlook the drinking and pot smoking in the beginning because I really liked her and the sex was great. But once the honeymoon phase was over, these habits started to irk me more often. She really had not changed all that much, I just noticed it more as we fell out of "lust" and into the "daily routine."
Like you, I started noticing my girl was "zoned out" on pot or wine (or Coronas) on many evenings, and your dinner scene brought back memories. Sometimes, I'd sit there and watch her get frustrated at herself, trying to perform a relatively routine or simple task. But like you, I didn't want to make a big deal out of it. I preferred her being zoned out, over having a big argument.
It's hard to make the case to a person that they have a problem when they are doing this on their "down time," and it's not affecting their job or finances all that much -- a functional alcoholic. When I did talk to her about it, she'd just stare at me and pout, or tell me that it was all in my head -- that I was over exaggerating and should loosen up.
If I showed her lots of affection and attention, she hardly did any of that stuff -- or hid it well. When I withdrew into my own world, she would find comfort in weed, booze, and cigs in the evenings. It felt like a Catch-22. I could get her to slow it down by being all lovely dovey with her, but I didn't feel like showing affection because of the bad habits -- and other stuff.
We started doing the "breakup get back together" thing. And then we just split. She ended up meeting some guy who was willing to stick in there and put in the time and effort to help her get her life back together. Our relationship was so damaged, and I had so much resentment (this was on and off for 7 years) that I just didn't have it in me (or love her enough) to try and work it out.
Another thing, in my case, her bad habits weren't the problem. When I met her (like in your case) she was already doing all those things. Other issues we were having just made them more obvious and bothersome to me.