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.
(..) Doyle, don't tell me he's an unemployed magician, amusing the neighborhood with his sleight of hand. Don't tell me that. It's too obvious and stupid a way to commit murder. In full view of windows? Then sit there smoking a cigar, waiting for the police to come and pick him up? (..)1954 Rear Window