But Guy says it was Cosima's "competitive" that nature got in the way of her forging friendships.
"I know Cosima struggled with some people but she was highly competitive, and I think that just drove a lot of people [away]," he told 9Honey Celebrity.
He added: "She obviously put the competition side first, whereas there were genuine friendships. Like me and Shannon Noll are mates, and I had a very close mate on the show, Levi [Kereama], who unfortunately passed on -- he was like my little brother. And there were so many others, like Paulini Curuenavuli, who I just got along with so well.
"I just think Cosima can be a little bit negative at times. People like to have a crack at Idol but it changed my life, so I'll never, ever slam it. It was my life source."
This article originally appeared on WHO.