Sweden said:AS computergeek said - common-law is not a problem. As long as you can prove that you have lived at least for 12 months together, then you're fine. In your case, it's almost 2 years, so it should not be a problem, both to "qualify" as common-law (12 months minimum, you have more) and to prove your relationship - if you have been living together as a couple for almost 2 years, and your partner has moved to your own country to be with you, it won't be difficult to prove that you are a couple... CIC will evaluate 2 things mostly : first, if you have serious intentions to return and establish yourself in Canada (that's the sponsorship part: intention to return to Canada + criminal background for your boyfriend), and second, if you're a real couple ( and well, after living together for 2 years in your country, there should not be much doubts), and your own background (clean criminal record etc).
The process is time-consuming and confusing at times, but you can get help from the forum if needed, and after a while, it starts to make more sense.
Good luck with the process,
Sweden
I have no idea (since im new here) how to give both of you a +1 u really make me feel more confident about the situation. Thanks!!! ;D