Hannah- I really enjoyed this story. I love how you can say so much by saying so little- you don't give us any access to Dean's thoughts, except through Lavender, but its very clear how he feels towards and about her throughout the story. Also the moments you've chosen to show their relationship and the way in which its changed, were very well picked out, None of them felt unnecessary, or dragged, and all were pertinent to the relationship you were exploring.
But what I loved most was your characterisation. I thought Lavender's reaction, to being 15 and getting asked to the ball, to not being quite able to deal with Dean having to run (although I also think it was unfair of him to have asked her to join him), and then the possibility that Dean and Seamus would die. I do however *think* that Seamus is seen talking to someone after the battle in the book, so that isn't quite canon, but I'm not sure (sorry) and the way you describe Lavender's emotions at the wake are very well done.
I must admit, when Dean interrupted Lavender and the guy I thought exactly what Lavender thought, but I liked the way his conversation showed he cared for her very deeply, and the idea that through one friend dying, and another not being able to deal with it well, he was losing both, was very poignant. I also liked the way you contrasted Lavender sleeping around, and Dean's running, and different ways of dealing with the events of the battle.
You are very good at writing sex scenes (I've said this about the Bookshop Owner's Gift). They are very sensual and the language you use is very original. I absolutely adore the description "his fingers ghosting instead across the pale, peach silk and tracing her scars beneath it like a man denied sight". It's just stunning. And very realistic of Lavender that given how uncomfortable she is with her scarred body, she'd want to remain in control.
As the flaws in their relationship, of Dean wanting more and Lavender being unwilling to give it, you showed their arguments, and the different sides, very well. In fact I don't think I sympathised with one over the other, as both had valid reasons for behaving in the way they did, which is a very difficult trick to pull off, but you did. The reconciliation scene, and them opening the gallery is a very romantic idea (although from first-hand experience I know this doesn't always work).
The one thing I would say (and its a very minor nitpick) is the forward slash in "t's an art gallery / or at least it will be.". It just didn't sound right in speech, and was rather jolting, given how good your dialogue had been up to this point. Also (and I know this isn't your fault) but the question mark symbols are annoying. If they have replaced a dash then by breaking the dash up- so it looks like this: -- will, hopefully, get rid of them (it does in my docs). Anyway Hannah, lovely story-Alex