Rhode - I understand what you are saying. I used to do the same thing...big gold star when my AH would take my car to have the oil changed without me asking. Or when I would come home and the laundry had been folded. Or when he finally painted the room I had been asking him to paint for a year. YAY! I thought that if I recognized the desirable behavior that it would make him feel good, feel confident, and that it would encourage more positive behavior and eventual sobriety.
The fact is, when we do that, we are using too much rational thought for irrational behavior and it only ends up driving US crazy in the end. It would be like trying repeatedly to unlock the door to your house with a car key. Just isn't going to work. We cannot be responsible for the behavior of others and to think that we can CHANGE their behavior is counterproductive to our own recovery and well-being. Codie recovery is about living your own life in as normal and healthy way as possible despite external circumstance you can't control.
I remember saying, when AH was in a period of abstinence, "I love it so much when you are sober. You are strong and sexy and the man of my dreams." That was true - I loved it when he wasn't actively using and I thought telling him would make all the difference. However, I would be so hurt and enraged when he relapsed because my motivation was displaced. I wasn't saying those things just to express my feelings but instead to give him praise and positive reinforcement that might "make the difference". However, unless someone has surrendered to their powerlessness over their addiction, it doesn't make a difference at all. In reality, I now realize that all I was really doing anyway was giving my AH reinforcement to continue using (because he obviously "had it under control").
If you appreciate the dinner she made, tell her as you would tell anyone else. Just be doing it because it is a true expression of YOUR feelings, not because you are over-analyzing and thinking it will have an impact on her future behavior or potential sobriety.
***I wanted to add that sometimes we don't always hear what we expect to hear (or maybe hope to hear) on this forum. The first few months I was here, I felt the sting of people's words. What I now realize is that there is so much truth here that it is painful at first. We have to crawl out from the warm, fuzzy blanket of our own denial and that can lead us into a very cold reality. However, once you acclimate, you find that there is a whole bunch of neat stuff you've been missing while you've been hiding under there.