Really, Todd?
You don't believe the rumors about Olive, fine ... but rather than believe that someone made them up, which any normal person would, you believe Olive started them herself and Brendan asked her to, because once in middle school Olive told people you kissed her because you asked her to?
This was a ridiculous way for Todd to 'find out' and know the truth.
So much in this movie is considered realistic, but if that's how someone's mind really worked, they would be considered paranoid or insane.