Grammar fix
main reason
most important reason
The biggest or most important reason for something happening or for a decision.
collocationB1common
Hear it in context
Notice where the phrase sounds natural.
The main reason I moved to this city was for a better job.
The main reason I prefer public transport is because it’s more convenient and better for the environment.
Fix the pattern
One small grammar move makes it sound right.
Not: The main reason of leaving was the pay.
Say: The main reason for leaving was the pay.
'Main reason FOR' something — not 'of'.
Which sounds natural?
Tap the one a native speaker would say.
'Main reason' is the plain everyday phrase; 'principal motivation' is essay-formal.
Build natural chunks
Words that usually travel with it.
the main reason + for/why
- for
- why
- behind
- is that