+1 what nathan said. When out shopping, make mental notes of what she likes - perfume, jeans, etc. Be VERY low-key about it, don't ask too many questions. Just observe, listen, maybe talk to her relatives or close friends for hints.
Then do what I'd do. Buy some badass lingerie for her that turns your crank. You'll both thank me!
But dude, that fugly coat, T F were you thinkin?
Come back anytime for more advice. Always glad to help!