Her reasons for leaving were 'obvious'. = It's 'obvious' why she left.
You are stating 'the obvious'. Tell me something I don't already know.
Her doctor immediately noticed the 'obvious' signs of the disease.
(..) from executing the crime of the century? No, no, no. Step away from that, please. How do you choose to congratulate the greatest criminal mind of our time? Do you tell me that l'm brilliant? Oh, no, that would be too obvious, I grant you. Charismatic? Fiendishly gifted? Try twisted! (..)1978 Superman