They started dating around the time they were filming Skins US. :D
We were unsure for a long time because James is no longer on twitter and Sofia rarely tweets about them, so there was no way of knowing for sure. But Sofia tweeted a picture of them together a few months ago and she hasn’t sounded broken hearted in any of her tweets… so, as far as we know, they still are.
Wow! What’s he like? :D