Don't think it's adult fiction, more young adult but anyway...here's what I remember
It was about a young English girl who goes to France, perhaps on exchange or to stay with friends of the family? She falls in love with a boy and they spend all summer together. He comes to London for a visit at one stage. They go back to France and he ends up dying of menengitis (I think). They are in their late teens I think. Set in present day (some 20 odd years ago now though).
I don't have burning desire to read it again, it just popped into my mind the other day and made me smile as I remember some bits of it being so sweet (like when they first kiss, in a boat at sea) and then so sad when he dies. She goes to see his body and recalls a small freckle on his finger. I think he has red hair!
Anyway, if anyone can help, that would be great!