Lawyer said, since it was not a committed relationship in that, there shouldn’t be issues. We weren’t sure of the relationship and our family didn’t know about it, also we didn’t publicly post about our relationship in social media too. It’s been almost a year that I got Pr and it was 6 months ago we decided to get married.
Well, good luck.
To me a few things stand out:
-'we weren't sure of the relationship' = there WAS a form of conjugal relationship.
This is EXACTLY why the concept of 'common law relationship' exists - people living together for 'years and years' and not making up their minds or having their own ideas about what constituted a committed relationship. (Yes, three years = years and years, as does moving together, etc). For a lawyer to claim that the lack of commitment doesn't make it common law is (to me) outright asinine; but people can argue anything.
-The relatively short period of time between you getting PR and getting married, as well as the continuity, argues against the point.
Now it may be possible to argue and present this in a (more) convincing way - there's an aspect of subjectivity - but it's not at all a given IRCC will accept this presentation.
For anyone else in this situation (but BEFORE one of the two becomes a PR): if in doubt DECLARE YOUR RELATIONSHIP and get the partner on your application, as unaccompanied if must be. (You're never
required to sponsor your partner, so there's no risk in that situation).
Or at minimum: have this conversation BEFORE - recognizing you might not be able to sponsor/be sponsored.