The agent we had seemed to have a bias against Jamaicans who have kids. During my interview he repeatedly told me how many cases they have where the dad has kids, divorces the Canadian to bring the mom over and how he has to "protect all Canadians". I think he told me that over 5 times.
If you have not done, write down in as much detail as you can remember - immediately - your best recollections of what was said during the interview.
Then I would say AT LEAST get a consult from a lawyer.
The point being here - in my view - that you have been given a rare opportunity here to challenge materially on basis that the agent TOLD YOU OUT LOUD, and REPEATEDLY, what his bias was, what he was looking for, and (arguably) did not evaluate as a separate case.
I'm not a lawyer - and you need the specific legal langauge for this. Your written recollections as soon as possible after the event are really important.
Separately, the core part of your claim - that your relationship is real - will need to be strengthened and demonstrated as much as possible.