Mari, 26, joined Flamengo on a permanent deal in 2019 before joining the Gunners on loan in January.
Speaking of his experience to the Guardian, Mari said: "You go [to City's training campus] for medicals each year – blood tests, urine, scans – but when I went to the Netherlands and Coruna, the [City] first team hadn't started pre-season, so there was no one there.
"You never cross paths. That can feel a bit strange, but City were transparent. The plan was always to go on loan.
"They help you find teams but never oblige you and the last word always has to be yours. After two years, I said I wanted to return to Spain, go step by step awaiting a chance in the Primera.
"Look, a player has to have one thing very clear: how much you're prepared to lose to be a professional.
"You have to ask yourself that question and be honest. It will never, ever be all lovely. Or all awful.
"My objective was clear: whether it was City or not, I was going to get to a big club. I was absolutely convinced, ever since I left home at 13.
"I never thought of giving up. Never. I've had really bad moments, but you can't ever leave something you love.
"Football might have thrown me out, but I was never going to throw it out."