I don't think the "I'm proud of you" is the right way to go...

Maybe either an open ended question, "I've noticed you cut back on wine, how's that working for you?"

Or, a report about its affects on YOU, "I've noticed you cut back on wine and for some reason that makes me feel more relaxed in the evening..."

Avoid the judgmental stuff which "I am proud of you" REEKS of...

Best,
Oldtimer

Best,
Oldtimer