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.
(..) I don't know what all this mean, - but I won't fail him. - You're afraid, Draco. You attempt to consider, but it's obvious, - let me assist you. - No. I was chosen. This is my moment. Unbreakable Vow. (..)2009 Harry Potter and the Half-Blood Prince