I liked this. I think it is the first Ron/Millicent story I've ever seen anywhere, and you really make this pairing work. Millicent's POV really shows how attractive Ron would be, bringing out a side of him we don't fully see in canon. And your comment that people don't always stay with what they thought they wanted at 17 is really driven home here.
I ended this feeling so pleased for Ron and Millicent, which is a tribute to the story: it really got me invested in them!