Blank White (2018)

John (35), realizes to be the murder of his wife Claire (30) while he is kidnapped in a cell. In the cell, John interacts with the jailer, who gives him white notes instead of food. In the meantime, in a dark office, Claire is writing on her desk. A man enters and they start to argue. These two storylines lead to the final twist where we get that the unknown man is actually John, her husband. He kills her because he has found her in his office signing divorce papers.