About a Turkish kid who goes from ancient Istanbul to Britain.

Set in ancient Istanbul about a thief who I believe is doing it to look after his family. One day his father comes back from somewhere and sends him away. He then ends up in Britain where he meets a boy who becomes his friend. And this boy married his crush. They're still young and in their teens. I remember this scene where his friend is getting married to his crush and he sees there is a girl sitting on the corner or all that merriment and weeping quietly. After that they fight some war or something. It was a bit of a convoluted story but very interesting nonetheless.