Essentially what Rohmer is saying with this film is that passively expecting things to happen without working for them in any way is foolish. Faith is a key theme in Rohmer's work and this might be taken as a sort of critique of blind faith. When the winemaker is thrust into these romantic entanglements she reacts like a petulant child instead of a mature adult. The logical plans of her wordly friends are a sharp contrast to her own naivety. Still, this isn't some cold rejection of her character; in spite of her flaws the winemaker still has some admirable traits and things work out well for her. This is the difference between Rohmer and certain other directors who attempt to analyze human nature: he never lets his ideas overcome the realistic boundaries of human behavior and thus avoids the all too common pitfalls of misanthropy and didacticism.
Like almost every Rohmer film I've seen, An Autumn's Tale expresses some truths about human nature with a captivating realism. However, this film didn't really speak to me the way some of his films do because I ultimately don't have much in common with the winemaker. It's still well worth watching, especially for people who have more in common with the central character.