I hate sad endings, but I really enjoy serious/sad/dark shows that explore human suffering? Which sounds messed up but I like shows that explore how we cope and heal and learn to love after tragic or traumatic things happen to us.
I've just started Just Between Lovers (which I think is on the path to a happy ending, fingers crossed) and I'd really like to find something that deals with the same sort of thing? If you aren't watching it it deals with the aftermath of an accident and how, years later, that accident has shaped and effected the lives of the people involved in it.