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.
(..) Wow! She sounds lovely! The truth is that I... I don't like people much. And they don't much like me. But why, with all your obvious wit and charm? Seriously, John. Mathematics... Mathematics is never going to lead you to a higher truth. And you know why? (..)2001 A Beautiful Mind