Ontario has never wanted to exit Canada as far as I know and I've lived here 49 years.

The unspoken part is Ontario feels they are Canada just like how Toronto is the center of the universe.

Ontario has never wanted to leave Canada. However, northern Ontario has wanted to split from southern Ontario and form its own province within Canada. Source: I was born and grew up in northwestern Ontario and there was a fair amount of dislike of southern Ontario, but also strong pro-Canadian sentiment. In summary:

Resource Revenue - Northern residents feel local profits from mining, forestry, and hydro generation are siphoned to Southern Ontario with insufficient local reinvestment.

Transportation & Services - Higher gas taxes, highway maintenance backlogs, winter road safety, and limited transit (e.g., the elimination of Trans-Canada Greyhound bus service. Many small towns on the Trans-Canada highway are now almost impossible to reach without a car, without spending a lot more time and money).

Policy Disconnect - One-size-fits-all regulations designed for urban Toronto often fit poorly in northern wilderness environments.

Political Power - Northern Ontario holds roughly 10–13 provincial seats out of 124, making it difficult for northern MPs or MPPs to influence policy regardless of who forms government.