The pair are close from Guardiola's time with the Serie B club.
"Guardiola had already told me he would take a year out," Corioni told TMW.
"Pep is a very intelligent man and had understood after four years he had no more motivation, so winning wouldn't have made a difference. He seemed thoroughly relaxed and normal.
"At this moment it is very likely he will stay out for a year and not work for a big club. I think he'd prefer to train a national team instead.
"Pep had already hinted he had decided not to train any more, while his assistant manager still had a Barcelona contract and could therefore be his replacement. Barça look for an internal solution.
"I don't think it'll be a huge problem for Barcelona, as the players are there. Pep made them play the best football and I don't think anyone can do better at Barça. Poetry and sentiment are important, but so are the results."