"I Was a Fool" is a song written and performed by Canadian duo Tegan and Sara, inspired by one of Rihanna's singles ,Unfaithful from her second studio album "A Girl like Me" (2006), written by who?
I Was a Fool:  Inspired by Rihanna's singles "Unfaithful" and "Umbrella", the song is about a woman who is in a troubled relationship but doing nothing to fix it, making her seem like a fool.
i don't know