It's actually a bit weird she wasn't a romance from the get-go. She's set up for the classic "save the lass and her family from the evil monsters" scenario. I swear that's a scenario. Really. Um, yeah. Seriously, you actually do more for this lady than any other NPC chick that can enter the party. You listen to her plea for help - without really knowing what you're getting into. You travel a good distance. You liberate a frickin' castle and save some of her friends and a family member. This puts you in the position of being terribly heroic, self-sacrificing, brave, and proven as committed to her interests. If your PC is a good looking guy (check the Charisma baby) then there are a lot of reasons she would possibly consider you as a worthy mate/partner/whatever. So, it's almost odd that she doesn't even really give your character a kiss on the cheek for what you've done. So maybe this is why she's such a sex symbol.
I've thought about this waaaayyyyy too much.