Flight fares and distance of the travel [duplicate]

I am based on Chennai and currently living in Toronto. I am planning to go to Switzerland from Chennai after some months ( once I back to Chennai).

Currently I am estimating my vacation cost ( 3-4 days stay in Switzerland , 4 members family).

Approximately, Switzerland is halfway from Chennai to Toronto ( based on distance ), So I expect the airfare to Swiss should be around 50-60% of the airfare of Chennai-Toronto. ( Assume, other than distance all factors are same ie. travel dates, weekdays, off/on season etc).

But I noticed that Chennai-Zurich costs almost 80% of Chennai-Toronto airfare. ( CAD 850+ compared to CAD 1100, if travel dates falls in Oct 2019).

How the airlines decide fares? As per my understanding distance is the most important factor.

Or Am I missing anything?