She 'went into mourning' for her dead husband. [=she began to mourn for her dead husband]
She is still 'mourning' her husband, who died last year.
She is still 'in mourning' for her dead husband.
(..) Listen. You've been running all your life. Terrible things happened to your family and you weep. You sit alone in a dark room, mourning their fates. You've been a bystander to tragedy from the day they executed your father. Stop being a bystander, you hear me? Stop running. (..)2015 TvShow: Game of Thrones Title: High Sparrow Season: 5 Episode 3